Answer
Inverse action: untying your shoelaces.
Work Step by Step
In loose terms,
let f(untied shoelace)=tied shoelace.
We want the inverse to be defined on tied shoelaces,
g(tied shoelace)=untied shoelace
So,
g(f (untied shoelace)=untied shoelace
and
f(g(tied shoelace)=tied shoelace.
[ f(g(x))=x and g(f(x))=x ]
Inverse action: untying your shoelaces.