Is 'delete' standard phraseology though?
Yes. The same verb is used in the 7110.65 and other FAA documents. For example, see the "NOTE" in section 5-7-4
An instruction to “resume normal speed” does not delete speed restrictions that are applicable to published procedures of upcoming segments of flight, unless specifically stated by ATC.
Likewise, see page two of this
InFO document (emphasis mine):
DELETE SPEED RESTRICTION
Cancels published speed restrictions.