Delete periods before end of sentence (5)
I believe the answer is:
erase
'delete' is the definition.
(I know that delete can be written as erase)
'periods before end of sentence' is the wordplay.
'periods' becomes 'eras' (periods of time).
'before' is a charade indicator (letters next to each other).
'end of' suggests the final letters.
The last letter of 'sentence' is 'e'.
'eras'+'e'='ERASE'
(Other definitions for erase that I've seen before include "Remove all traces of" , "Destroy recording on audio or video tape" , "Remove permanently" , "Rub out, expunge" , "To remove all trace" .)