When your campaign comes to an end, you can easily remove the ability to process donations while keeping the campaign enabled online.
When the donation form is disabled, the Donate button is removed from your campaign site.
Here's how you can disable donations for your campaign:
Step 1: Under Campaigns, select the Settings of the campaign you wish to edit.
Step 2: Under Donation Form, select Disable Form and Confirm.
Now, you can keep your campaign online and no more donations can come through your site!