I just had this same issue.
I didn’t have anything in my search bar like Localbusdriver said, but I DID have the “find results” tab selected as active despite not having searched for anything this work session and despite that the field was blank under “find results”. I might have saved and closed the UE 5 editor last time with a search having been completed and sitting in the results field, and perhaps it was visually blank when I reopened the tool just now despite the engine somehow thinking it wasn’t.
Anyway, as soon as I clicked a different tab in the same section of my UE5 UI to make “find results” go inactive it stopped blocking me from deleting anything. For me I selected “compiler results” which I keep right next to “find results” as a tab.
Anyway, good find localbusdriver. You solved my issue.