how to remove episodes that were added via missing episode fetcher?

[Iacov]

hes

i used to have the missing episodes fetcher active becase I thought it was a good idea but I don't want to use it anymore. 
the issue is, when deactivating the missing episode fetcher, it's data is not gone... so missing episodes still get displayed even to that point, that if I add a formerly missing episode, that I now have duplicate entries... the actual episode and the "missing" one

how can I get rid of the data that was created by the missing episode fetcher?