Because you want to delete a whole paragraph (multiline string), you have to use ^p (DOS files) or ^n (Unix files) as placeholder for every line break in the find string.
You could also open one of the files and select the paragraph. Then open the Replace In Files dialog and the selected paragraph will be automatically pasted in the find field with small rectangle characters which are the CR and LF characters.
If your paragraph is too large (more than 1023 characters) you have to copy the selected paragraph to the clipboard and use ^c in the find field of the Replace In Files dialog.
Regular expression search must be unchecked for all 3 methods!
Best regards from an UC/UE/UES for Windows user from Austria