If I want to cancel a square a.k.a 4^2 do I multiply or add it to the square route of said number (4 here)
You don't add or multiply the square root, you 'take' the square root.
I.e you may have $\displaystyle x^2 = 81$ and you want to find $\displaystyle x$
which is the same as
$\displaystyle x^2 = 9^2$
now you can see you can take the square root of both sides.
$\displaystyle \sqrt{x^2} = \sqrt{9^2}$
which in turns yields
$\displaystyle x = 9$
As square and square root are opposites.
Now go ahead and change the world!