Definition of cancelling:
(v) :
(transitive) To invalidate or annul something.
(v) :
(transitive, media) To stop production of a programme.
(v) :
(transitive, neologism) To cease to provide financial or moral support to (someone deemed unacceptable); to disinvite. Compare cancel culture.
(v) :
(transitive) To cross out something with lines etc.
(v) :
(transitive) To mark something (such as a used postage stamp) so that it can't be reused.
(v) :
(transitive, mathematics) To remove a common factor from both the numerator and denominator of a fraction, or from both sides of an equation.