If you are leaving the masjid, this is the simple dua you need to read in Arabic below
Dua for leaving mosque transliteration
The transliteration to the supplication for leaving the masjid is,
Bismillaahi wassalaatu wassalaamu ‘alaa Rasoolilaahi, Allahumma ‘innee ‘as’aluka min fadhlika, Allaahumma’simnee minash-shaytaanir-rajeem
Also READ;- Dua For Entering and Leaving the Masjid
Dua for leaving Masjid in English
Here is the meaning of the above dua in english.
In the Name of Allah, and peace and blessings be upon the Messenger of Allah. O Allah, I ask for Your favor, O Allah, protect me from Satan the outcast.