There’s a link above the post editor that explains how to put them in your posts and lots of other useful things like code blocks. Please read and use it.
They are top level collections. I was assuming, that Removecollection would work on folders inside coll://, and also on contents of those. I have also tried a delete filter inside the command, but also couldn't figure out the partial match for that. So basically i want to make a button to remove collection items, that partially match a certain name.