Probably worth putting this in the Welcome Thread:
Modding for games works as follows:
1.) You may add mods to your game mostly without issue. (As long as all mods are compatible with each other, which is a separate issue.)
2.) If you save your game with a mod running, that mod will leave reference data in your save state. Meaning: even if you remove a mod later on, the reference data will remain in your saved games forever more after that point. (This is a major source of people's problems with mods. It's not adding mods that's an issue.) Removing mods after the game has been saved with them running can create all sorts of issues.
3.) So, importantly, once you've used mods and saved your game, removing them falls somewhere between not recommended and certain doom. Best bet is to save your game, back up 3 save files or so, and try out some new mods. Then, after you're done experimenting, if you like the mods, keep playing with the idea that you're going to use them for the rest of that playthrough. If not, remove them, delete all of the quicksave and autosave files, and restore those backup saves that were made before you installed the mods. That's the only way to ensure your game is not corrupted with bad reference data.
4.) This is true of all mods for all games. Not all mods are going to create issues if removed, but the more mods you use and/or the more complex they are -- if removed -- you will wind up with broken reference data in your save files. The only way to fix this if it causes issues is to restore exactly the same mod library as you were using originally...or start a brand new game.