Please see How do I delete a bookmark?

feer56, that article is for the desktop Firefox.

https://support.mozilla.org/en-US/products/mobile/bookmarks

hi Wilma45, if this is still a problem, KadirTopal has given a solution here: https://support.mozilla.org/en-US/questions/949430

Shortly, to delete a bookmark you simply tap and hold, then from the context menu you can select "delete" to remove the bookmarks.

hope that helped you