Like the title says, I see no grooves or notches for inserting a "key" or any other tool to remove the aerator on this faucet. Pictures below.
In theory you can just crank it off with fingers. No doubt years of accumulated minerals have stuck it good.
Wrap it with an old rubber jar opener two layers thick, then grab it gently with a Vice-Grip or ChannelLock pliers. Lefty loosey.
You could also use electrical or duct tape, but that should be half a dozen layers thick to prevent damage to the finish.
When you put it back, just finger-tighten it.