# Unset Built-in Functions (Times, Dot, etc)

Yes, I know, I should never actually do this in a package or something. But I'm curious - how could I undefine Times or Plus or the like? I tried Unprotect and Clear, but that didn't seem to work.

• Related: (19126), (89832) – Michael E2 Dec 5 '16 at 11:41
• Also: 48929 – Kuba Dec 5 '16 at 11:43
• Hm. Interesting, but that doesn't answer the question for Dot, which as far as I know isn't defined this way and still refuses to be redefined. – linkhyrule5 Dec 5 '16 at 11:47
• Why? Unprotect[Dot]; Dot[x_, y_] := x^2 + y^2; Protect[Dot]; then Dot[a, b] yields $a^2+b^2$, and Dot[2, 5] gives $29$. Although this trick indeed doesn't work for Plus. – corey979 Dec 5 '16 at 13:27