A reminder for when you really want to destroy a whole bunch of stuff...

Find out what tags you have locally:

david$ git tag
v1.0.0
v1.0.1
v1.1.0

Delete them all:

david$ git tag -d v1.0.0 v1.0.1 v1.1.0

Push all those deletes to the remote system:

david$ git push origin :refs/tags/v1.0.0 :refs/tags/v1.0.1 :refs/tags/v1.1.0

That's it. Destruction complete.