Do no use "of" after another preposition.

Preferred
Inside the 40-yard line
Outside the realm of possibility

Not the Best
Inside of the 40-yard line
Outside of the realm of possibility

If you're telling your reader how do something, you do not need to use "on" or "in."

Preferred
Click the right mouse button. 
Click OK.
Press Delete.
Type your password.

Not the Best
Click on the right mouse button
Click on OK.
Press on the Delete key.
Type in your password.