How to remove all tags in vBulletin?
To remove all vBulletin tags, access the vBulletin database and truncate the content of the tag table.
Run the following MySQL query:
TRUNCATE TABLE tag;
(You can run a MySQL query using phpMyAdmin. More information on how to do this can be found in our tutorial How to execute MySQL queries with phpMyAdmin.)
This way the table structure will be preserved but all tag records will be erased.