Im guessing
@sepide has installed the TWRP app as opposed to flashing a custom recovery as that would require a pc. The first time I rooted (Galaxy S3) was with an app. It gave me some experience in regards to android root and at firsy I was extremely great full to finally have root access. That lasted about a day lol. For the next three or four weeks I was battling that dam app for control. It was a mimic of SuperSu without the app controls. Furthermore it didn't even have an icon, just a pop up allow, grant, promp and no app interface. It foced me to learn the file systems (so what ) and replace it with SuperSu. Even so I had no idea what possible malware was left in the file system. A few months later, I used a pc program to flash
Cyanogen Recovery (yes that long ago lol). I now use TWRP custom recovery and have no use for the app itself.