Help How to Block sdcard device on Asus Zenpad 10

[Android Question]

Hi to all.

Normally I'm not an Android user but for work I need to set some Asus Zenpad 10.

Asus Zenpad 10 with android 5.0.2 don't allow to set more user on it. I rooted the zenpad (I found information on forum surfing on the web) and i used application to do this work.

Now I need to block sd card use. Noone can use your sd card on the tablet.
How can I do this? Where I have to write string and how can I do this?

Thanks a lot for your support