I just quickly tried this. So I don't know if there any repercussions, but it does not appear so.
But it takes a query.
The following will delete all watched items for a user.
Just change the user ID number to what you are.
Quote
DELETE FROM `ubbt_WATCH_LISTS` WHERE `USER_ID`=263

Now of course I am using the ubbt default prefix so if yours is different change that also.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers