discharge

To discharge something is to release it or let it go, especially all at once.

Example: Discharging steam prevented pressure from building.

When a gun goes off, it is said to discharge.

Example: He took aim and discharged his gun.

When you are discharged, you are allowed to leave.

Example: I was honorably discharged at the end of the war.

When a debt or obligation is been met or is ended, it is discharged.

Example: We made the last payment, and the loan was discharged.

Discharge is the opposite of charge for things like batteries and reservoirs.

Example: I forgot to plug in my phone and the battery totally discharged.