How do I remove the unused dots from the scanned image in Gimp?

[KaiAeon]

I'm preparing for this period's Lite Challenge and need to remove the unused dots in the image below using Gimp. Will you please advise?

Titans Prison01 small.png

[Redrobes]

Cant you just paint some white over them like below or is there something more intricate about it that I am missing - for example, you have loads and loads of images like this that you need to perform that process on ?

[KaiAeon]

Hi RedRobes, Thanks for the quick response.

After posing the question, I tried using a layer mask and a soft brush to brush the dungeon onto a white background and succeeded. Your way works too.

Titans Prison01 small white.png