@xxx78 Well, I have multiple GTA V Folders in my Steam library. For example, "Grand Theft Auto V" is the directory Steam is pointed to, to open the game. So, I have two other folders named "Grand Theft Auto V Redux" and "Grand Theft Auto Mods". All I do, is rename the folder I want to play with and change the original one to "Grand Theft Auto clean". I also make sure my updates are turned off. So, if I haven't launched GTA V in a while, I make sure there's not an update and I only update my "clean" version.
I hope this helps!