To archive your custom audience you can follow the below steps.
Step 1: Navigate to your Google Analytics 4 property and click on the ‘Audiences’ menu under ‘Configure’.
You will see a list of available audiences.
Step 2: Now hover your mouse over the audience which you want to edit. Click on the three vertical dots.
Step 3: A pop up will appear like below. Click on ‘Archive’.
Step 4: A pop up will appear like below to confirm your action. Click on Archive’
You are done! Your audience will no longer appear in the audience list.