Welcome to Workshop. It's fantastic to have you join us. I trust you will receive lots of fantastic advice and inspiration from our community members, both for this project and for many to come in the future.
It might be helpful if you clarified what the residue is from. Did you remove wallpaper?
I'm guessing kids bedroom? Kids love stickers!
I would use sandpaper and a sanding block. If any glue still stubbonly refuses to budge then an electric hand sander should finish it off.
Many thanks for joining in the discussion and sharing some advice. Much appreciated. Let me also extend a very warm welcome to Workshop. It's great to have you join the community. It sounds like you have plenty of experience to share. I'm looking forward to reading about your projects and plans. Please feel free to post whenever you need a hand or have something to share.