TT #250 · Parshas Tazria · Aliyah 7 · Passuk 46
English: All the days that the affliction is upon him he shall be impure; he is impure. He shall dwell alone; his dwelling shall be outside the camp.
Torah Temimah cites Sifra (Toras Kohanim) for the rule that deliberate removal of the lesion does not exempt a person from impurity.
Sifra — Vayikra 13, Midrash Sefer
English: Could this rule apply even if the person deliberately cut off the baheret? The phrase “all the days” teaches that deliberate removal does not exempt him.
Textual derivation
Although the preceding unit excludes days after a lesion has been removed, that does not permit a person to evade the impurity rules by deliberately cutting it off; “all the days” preserves the rule against intentional removal.