For a traditional rental, there is nothing specific you have to do on Getaround to end the rental. You simply have to complete the agreement with the owner at the end of the rental, then sign it.
For an Getaround Connect rental, you have to return the vehicle to the location indicated in the vehicle details. Once you’ve parked, go to Your rentals, select the relevant rental and tap ‘View on Getaround Connect’. Then tap ‘End rental’. You will be guided step by step.