You will not be able to use existing save games without any mods that they were once dependent upon. More than likely you'll Crash to Desktop if you try.

If you want to get rid of the mod, however, first I'd go into DOSEE, delete all your save games (unless you like the idea of crashing to the desktop if you use them by accident without the mod installed and activated), then deactivate that mod by un-checking it under the Mod menu from the Main Menu.

Next, open up File Explorer and navigate to the following directory:

Documents > Larian Studios > Divinity Original Sin Enhanced Edition

The file you want to delete should be called something like:
epic_encounters_071a986c-9bfa-425e-ac72-7e26177c08f6.pak