Android - How do I disable the Mobile Hotspot feature?

I managed to solve this without deleting hostapd file (with this method you can easily reactivate hotspot functionality renaming hostapd back to its original name).

1. Root your phone
2. Open up adb connection
3. Enter these commands:

   su
   cd system
   cd bin
   mount -o rw,remount /system
   mv hostapd inactive_hostapd
   mount -o ro,remount /system
   

4. Reboot your phone and you're ready to go.

If you want hotspot functionality back to your phone, just rename it back to 'hostapd' (mv inactive_hostapd hostapd).

Tested on Motorola Moto C Plus.

Erase this file (with root): system/bin/hostapd

In addition to the other answers, I'd like to add that you can alternatively remove the execution permission from that file:

su
mount -o rw,remount /system
chmod 0644 /system/bin/hostapd

This approach looks more Unix-styled.

To restore it, do the same commands again, but use 0755 instead of 0644 (i.e. put the execute permission back).