BlueBrid

Hello everyone I'm trying to figure out how to best edit my PDF slides. I write on them and I cannot figure out how to delete what I wrote. As far as I can see there is no erase function such as with the sketches. This is unfortunate, since now I can only go back one step or delete all annotations, but I would like to know how I can select specific lines and sections and only delete those. Is there such a function?