ctrl+a, choose "Remove" to uninstall all mods. If you also wants to delete the mod-archives choose "Delete archive" in the dialogue that opens-up after choosing Remove on all mods.
To be even more extreme, you can also delete all save-games and delete all profiles.
Game and mod-folder must be on the same drive, so you should do something like:
1: In Vortex, on mods-tab hit "purge". 2: Exit Vortex. 3: In Steam, move Skyrim to another drive. 4: Run Skyrim launcher once to setup registry etc. 5: Re-start Vortex to detect new location of Skyrim. 6: Just to be on the safe side re-start Vortex. 7: In Vortex click Settings, Mods, specify new location of "Mod Staging Folder" on the new drive, and Vortex should move all files for you. Note, this can take a long time. 8: On mods tab, Deploy.
