I just cleaned up your OP in bulk by matching this following regex pattern:
\[url=https\://flic.kr/p/\w*+]\w[^,]*+, on Flickr
and replacing all instances of it with a null character.
The only assumption this pattern makes is that your Flickr image names all start with an alphanumeric character, and do not contain a comma. If your images did in fact contain commas then I would have to replace the very efficient possessive tail pattern [^,]*+, on Flickr with something like .*?, on Flickr which would still fail if any of your image titles contained the phrase ", on Flickr"