Webhook installed by a WIP add-ons are not deleted

[gabhijit]

I am working on a bitbucket cloud add-on where the descriptor mentions about webhook. While, I am iterating over application, at some points I might have messed up with the 'lifecycle' events. Consequently the webhooks created during adding th add-on are not recycled. I am at a point where I have about 20 webhooks on every repository in my account and they are all "Read Only" (likely they are all fired as well). I just want to 'cleanup' all the webooks. Simply un-installing the app didn't help at all. 

Is there a known way of cleaning the webhooks so installed?

Likely, this is a bug ?

Thanks in advance

-abhijit