Some types of diapers can be composted completely while others require the SAP to just be removed to compost.
To compost diapers they must be ripped apart or shredded up in a machine.
The diaper cannot just be placed into a compost pile as a whole diaper or it won't break down properly.
In most other disposable diapers that are not composting type diapers you can rip open the disposable diaper and compost the SAP in the diaper.
Then throw the plastic part of the diaper away.
Diapers that are advertised as composting diapers can be composted by tearing the diaper up or shredding the diaper up and placing all the diaper parts in the compost pile.
The diaper needs to be ripped apart or shredded for the diaper to compost properly.
You can also just bury the entire diaper in the ground if you have no trash service.
Or place the diaper in a burn pit or burn barrel and with a hot enough fire the diaper can eventually burn although it may take a few fires for the diapers to burn.