You will first need to enter the path to your scenery.cfg.
Once that is done. The program will show you what scenery areas you have installed, from default to payware and freeware.
If errors are present, it will show you with a Red Cross, making problem easily identifiable, and from there you can either delete the entry from the CFG or understand how best to correct it.
You could reorganise your Scenery library and activate or deactivate areas as you need, so things aren’t loaded without needing to be.
Many SCE tutorials can be found on YouTube, here’s a link to one of them:
https://youtu.be/W-DMMMse3UAPlease don’t uninstall FSX, I’m sure it’s correctable!