Here is a simple way of removing the carrier branding on the S4 (720) & (720T).
You will need to root your device or have a rooted ROM flashed on your device.
The file that controls branding is located in the Carrier Partition. The file name is Chameleon.xml.
You will need to edit all lines that show "Sprint" only. Save the file in the download folder of your mobile device and download ES FILE EXPLORER from the Play Store. Please make sure to mount all directories and show hidden files. Copy the xml file to the Carrier Partition and overwrite the existing Chameleon.xml file. You will then need to change the permissions to the xml file. You will only change "Other" to ready only. After you have applied that change reboot the phone or factory reset and the lock-screen & notification bar should now show the name you entered in the xml file.
<?xml version='1.0' encoding='utf-8' ?>
<ChameleonData>
<Operators>
<EnabledAppsVvm>1</EnabledAppsVvm>
<CarrierLegal>/carrier/data/app/Settings/</CarrierLegal>
<TetheredData>3</TetheredData>
<BrandAlpha>Sprint</BrandAlpha>
<LaunchZone>1</LaunchZone>
<AndroidOperatorNetworkCode>310120</AndroidOperatorNetworkCode>
<SubscriberCarrierId>2012083001</SubscriberCarrierId>
<PresetMessage>/carrier/data/app/mms/</PresetMessage>
<LaunchId>1</LaunchId>
<DiagMslReq>0</DiagMslReq>
</Operators>
<Browser>
<UaProfUrl>http://device.sprintpcs.com</UaProfUrl>
<SearchEngine>http://www.google.com/search</SearchEngine>
<HomePage>http://sprint.com/powerdeck,SprintWEB</HomePage>
</Browser>
<WiFi>
<Ssid>null</Ssid>
<GsmMaxUsers>1</GsmMaxUsers>
<IntRoamMaxUsers>8</IntRoamMaxUsers>
<MaxUsers>8</MaxUsers>
<DomRoamMaxUsers>8</DomRoamMaxUsers>
</WiFi>
<CallIntercept>
<Fourth>null</Fourth>
<Fifth>null</Fifth>
<Third>null</Third>
<Second>611,null,null,#Intent;action=com.sprint.zone.DSA_ACTIVITY;type=vnd.sprint.zone/vnd.sprint.zone.main;component=com.sprint.zone/.PageMain;S.com.sprint.zone.source=611;end</Second>
<Eighth>null</Eighth>
<Sixth>null</Sixth>
<Ninth>null</Ninth>
<Seventh>null</Seventh>
<First>*2,null,null,#Intent;action=com.sprint.zone.DSA_ACTIVITY;type=vnd.sprint.zone/vnd.sprint.zone.main;component=com.sprint.zone/.PageMain;S.com.sprint.zone.source=*2;end</First>
<Twelfth>null</Twelfth>
<Tenth>null</Tenth>
<Eleventh>null</Eleventh>
</CallIntercept>
<AndroidClient>
<Market>android-sprint-us</Market>
<Youtube>android-sprint-us</Youtube>
<MobileSearch>android-sprint-us</MobileSearch>
</AndroidClient>
<Mms>
<Proxy>68.28.31.7:80</Proxy>
<ServerUrl>http://mms.sprintpcs.com</ServerUrl>
</Mms>
<RoamPref>
<MenuDisplay>1</MenuDisplay>
<HomeOnly>0</HomeOnly>
</RoamPref>
<Contact>
<Fourth>null</Fourth>
<Fifth>null</Fifth>
<Sixth>null</Sixth>
<Third>null</Third>
<Second>null</Second>
<First>null</First>
</Contact>
<Adc>
<Fifth>null</Fifth>
<Fourth>null</Fourth>
<Third>0,Sprint Wireless Operator</Third>
<Second>*4,Sprint Wireless Account Information</Second>
<Eighth>null</Eighth>
<Sixth>null</Sixth>
<Ninth>null</Ninth>
<Seventh>null</Seventh>
<First>*2,Sprint Customer Service</First>
<Twelfth>null</Twelfth>
<Eleventh>null</Eleventh>
<Tenth>null</Tenth>
</Adc>
</ChameleonData>
You will need to root your device or have a rooted ROM flashed on your device.
The file that controls branding is located in the Carrier Partition. The file name is Chameleon.xml.
You will need to edit all lines that show "Sprint" only. Save the file in the download folder of your mobile device and download ES FILE EXPLORER from the Play Store. Please make sure to mount all directories and show hidden files. Copy the xml file to the Carrier Partition and overwrite the existing Chameleon.xml file. You will then need to change the permissions to the xml file. You will only change "Other" to ready only. After you have applied that change reboot the phone or factory reset and the lock-screen & notification bar should now show the name you entered in the xml file.
<?xml version='1.0' encoding='utf-8' ?>
<ChameleonData>
<Operators>
<EnabledAppsVvm>1</EnabledAppsVvm>
<CarrierLegal>/carrier/data/app/Settings/</CarrierLegal>
<TetheredData>3</TetheredData>
<BrandAlpha>Sprint</BrandAlpha>
<LaunchZone>1</LaunchZone>
<AndroidOperatorNetworkCode>310120</AndroidOperatorNetworkCode>
<SubscriberCarrierId>2012083001</SubscriberCarrierId>
<PresetMessage>/carrier/data/app/mms/</PresetMessage>
<LaunchId>1</LaunchId>
<DiagMslReq>0</DiagMslReq>
</Operators>
<Browser>
<UaProfUrl>http://device.sprintpcs.com</UaProfUrl>
<SearchEngine>http://www.google.com/search</SearchEngine>
<HomePage>http://sprint.com/powerdeck,SprintWEB</HomePage>
</Browser>
<WiFi>
<Ssid>null</Ssid>
<GsmMaxUsers>1</GsmMaxUsers>
<IntRoamMaxUsers>8</IntRoamMaxUsers>
<MaxUsers>8</MaxUsers>
<DomRoamMaxUsers>8</DomRoamMaxUsers>
</WiFi>
<CallIntercept>
<Fourth>null</Fourth>
<Fifth>null</Fifth>
<Third>null</Third>
<Second>611,null,null,#Intent;action=com.sprint.zone.DSA_ACTIVITY;type=vnd.sprint.zone/vnd.sprint.zone.main;component=com.sprint.zone/.PageMain;S.com.sprint.zone.source=611;end</Second>
<Eighth>null</Eighth>
<Sixth>null</Sixth>
<Ninth>null</Ninth>
<Seventh>null</Seventh>
<First>*2,null,null,#Intent;action=com.sprint.zone.DSA_ACTIVITY;type=vnd.sprint.zone/vnd.sprint.zone.main;component=com.sprint.zone/.PageMain;S.com.sprint.zone.source=*2;end</First>
<Twelfth>null</Twelfth>
<Tenth>null</Tenth>
<Eleventh>null</Eleventh>
</CallIntercept>
<AndroidClient>
<Market>android-sprint-us</Market>
<Youtube>android-sprint-us</Youtube>
<MobileSearch>android-sprint-us</MobileSearch>
</AndroidClient>
<Mms>
<Proxy>68.28.31.7:80</Proxy>
<ServerUrl>http://mms.sprintpcs.com</ServerUrl>
</Mms>
<RoamPref>
<MenuDisplay>1</MenuDisplay>
<HomeOnly>0</HomeOnly>
</RoamPref>
<Contact>
<Fourth>null</Fourth>
<Fifth>null</Fifth>
<Sixth>null</Sixth>
<Third>null</Third>
<Second>null</Second>
<First>null</First>
</Contact>
<Adc>
<Fifth>null</Fifth>
<Fourth>null</Fourth>
<Third>0,Sprint Wireless Operator</Third>
<Second>*4,Sprint Wireless Account Information</Second>
<Eighth>null</Eighth>
<Sixth>null</Sixth>
<Ninth>null</Ninth>
<Seventh>null</Seventh>
<First>*2,Sprint Customer Service</First>
<Twelfth>null</Twelfth>
<Eleventh>null</Eleventh>
<Tenth>null</Tenth>
</Adc>
</ChameleonData>