First click the down arrow to the right of the icons at the top of the page.
Next, click "Settings."
Then click "Apps" in the lefthand menu.
To remove Collage.com, click the X next to the app.
First go to Edit Profile in your Instagram account.
Next go to Manage Applications. Find Collage.com and hit the 'Revoke Access' button on the right.
To disconnect Collage from Google Photos, go to myaccount.google.com/security and scroll to the "Apps with account access" section and click "Manage Apps."
Select Collage.com from the app list and then click "Remove Access" to revoke sharing with Collage.com.