College kid I know has a one year lease on an apartment. His dad co-signed the lease. He left school and moved out of state because of a girl and now the dad is stuck with about 5 months worth of rent.

Any way for dad getting out of the lease without damaging his credit?

It is not just going to be a credit hit.
But also a judgement against him

Talk to the landlord. make sure the place is ready to show. Ask for mercy.

Then there are other ways. But less honorable.

Dad should offer to buy out the lease. Or get fucked.

Talk to the landlord to see if he will be willing to end the lease, buy out the remainder of the lease, or something in between.  I would be having my son kick in some as well.

Depending on the terms of the lease, most have provisions to “buy out” of a lease which is usually 2 months rent.  
It’s for unforeseen circumstances which force you to relocate, like military service, job loss or job change, death in the family etc.

In many states, once the apartment is relet the lease to the previous tenant is terminated.

With the current housing situation I can't see a landlord having troubles getting a new tenant in there immediately. Of course there is incentive to keep it empty and keep the lessee paying the bill so it's best if he talks to the landlord to feel out what they would do. Of course, if it's an "all utilities paid" place, those costs are wrapped into the lease payment so there is even more incentive for them to keep it empty and turn the heat off and keep collecting the lease payment.

ETA, if that were my son he is on the hook for the payments. If he doesn't pay and I'm forced to pay to protect my credit, I'm amending my trust to read, "Johnny gets his share of the assets minus $XYZ and compounded interest at the rate of 10% from January 2023."

Read the lease!
The terms for breaking the lease will be clearly stated.
Make sure you also read any addendums.
When we broke my daughters college apartment lease in the middle of Covid, it cost us two months rent.
But that was better than the six months remaining on the lease.

Check the lease terms against state statutes for residential rental properties.