Check this video:
http://www.youtube.com/watch?v=ryGIv8KQVIE
The poster included a bit.ly link in the description to what seems to be a GB stock image (over 300MB, which seems about right when you include all the T-Mobile crapware). My guess is you will need to replace CWM with the stock recovery for this to work with your enterprise app.
EDIT: here is the description from the video...
This video shows how to restore your T-Mobile G2x back to stock settings. This is helpful if you need to send it back to T-Mobile with your warranty still intact. Let me know if you have any questions!
1) Install stock backup
2) Restore stock recovery image (replace ClockworkMod Recovery Image)
3) Unroot
This video assumes:
- You have SuperOneClick
- You flashed ClockworkMod Recovery (the real way)
- You have One-Click-G2x-recovery-flash
- Your phone is rooted
- You have a custom rom installed (CM7 for example)
Link to Stock Data Backup:
(No Longer Working)
http://www.megaupload.com/?d=215BDWPA
(Use This Instead)
http://bit.ly/yct5tQ
Place this zip on the SD card. In ClockworkMod Recovery choose 'Install zip from sd card'