Lemmy Support

For some reason on my self hosted lemmy instance, I've managed to accumulate about 50GB worth of data inside my pictrs docker volume. I'm the only person on my instance and I've never uploaded any photos to my server other than my profile photo, profile banner, and site logo. Shouldn't all photos be hosted on other instances?

If it is not safe to simply delete the folders within the _data folder, how would I go about clearing out these files without it harming my server? Thanks in advance, as you can probably tell, I'm definitely new to self hosting my own social services. Thank you!