Generally glass coating agent should wipe off 10 minutes after getting dry.
However if you leave for a long time, it remains residue or causes unevenness.
The picture shows difficulty of removing agent.
Frankly to say, glass coating agent is formulated water repellent agent dissolve into solvent.
So, dissolve adhered ingredient with same solvent.
Once liquid gets whiten, firmly wipe it off immediately.
Beware of applying in high temperature and strong sunlight, because it gets dry so fast.
In case of leaving for a long time or fluorine type glass coating agent cannot remove enough. Then use glass compound to polish.