How to clean a reusable bottle with mold or sunscreen inside

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Cleaning the bottle thoroughly with soap or bleach
2. 2
   Throwing the bottle away and getting a new one
3. 3
   Scrape or wipe out visible lotion, rinse with plenty of water, and soak or wash in soapy water.
4. 4
   Use micellar water, makeup remover, or Dawn dish soap.
5. 5
   Using miniature interdental flossers
6. 6
   Checking manufacturer videos on YouTube
7. 7
   Pulling out silicone flaps/gaskets and soaking in warm water with oxiclean
8. 8
   Filling the lid with a 50/50 water and white vinegar solution overnight
9. 9
   Using pipe cleaners, wire brushes, or unfolded paperclips wrapped in floss
10. 10
    Soaking parts in dental cleaning tablets
11. 11
    Washing thoroughly with dish soap multiple times
12. 12
    Soaking overnight in vinegar
13. 13
    Soaking overnight with water and a small amount of bleach
14. 14
    Scrubbing with a brush and a sponge with soap
15. 15
    Picking at the stain with a finger
16. 16
    Using ball bearings or marbles with cleaner while swirling on its side
17. 17
    Using a bottle brush
18. 18
    Using chemclean soaked in warm water for an hour or two
19. 19
    Using paint mixing balls from game stores

In their words

Unedited, most upvoted first, each linked to the thread it came from.