First of all welcome to the cr.
If a persons tshuva was really sincere then these images can be viewed as a good thing.
Hashem doesn’t erase memory once the tshuva was accepted but rather He turns them into stepping stones for growth. The yetzer hara puts the images in your mind cuz he wants you to feel disgusted with yourself, and say uch I was so bad watz the point, and go back to your old ways. But instead if you take that image and tell yourself, wow I came far since then and I have no interest in falling back, then you’re squashing the y’h and it will only strengthen your resolve to keep on growing!
Hatzlocha!!