You don’t slap a kid. If the child comes 1000 times, you call the cops 1000 times. Eventually the kid will tire of being hauled out by the cops.
You could sue the mother for reimbursement for each documented time the kid uses the pool.
“911 what’s your emergency”
“A non-resident kid is using our pool!”
“LOLOLOL...ha, ha, ha. Call the apartment manager, not the police.”
“If the child comes 1000 times, you call the cops 1000 times. Eventually the kid will tire of being hauled out by the cops.”
You assume the cops will come. Even once.
Both of you are living by the “old rules”.
They no longer apply.
The manager did not assault a child.
The manager took out the trash.