You can remove the background, resize, and reposition your logo using the "Creative Studio Editor".
Select the Edit button under your ad you want to edit
Select Creative Studio Editor.
Select your logo and click 'Ungroup Objects' in the top right corner.
Now you can select the white background on its own. Once selected, delete it.
Select your logo, then resize and move it as you like.
If you need any further assistance, feel free to reach out to our Customer Success Team! We're always happy to help 😊.