I am the owner. Can I ask the developer for the property fee of the unsold garage?

It depends on the agreement on unsold parking spaces in the previous property service agreement.

All the work of the property is centered on the property service contract, based on both the construction unit (developer) and the owner.

According to Article 42 of the Property Management Regulations, the owner shall pay the property service fee in accordance with the property service contract. If the owner and the user of the property agree that the user of the property shall pay the property service fee, the owner shall bear joint and several liability from the agreement.

Property that has been completed but has not been sold or handed over to the property buyer shall be paid by the construction unit.

What you said should be collected by the construction unit (developer).