You can incrementally delete your posts and interactions while backing them up. Once done, you can request your user data to verify that deletion has taken place, and then cancel the account.

https://github.com/j0be/PowerDeleteSuite , this and other tools make it easy to manage.

Reddit has hamfistedly broken whatever value it once had as a platform for long form discussion, with the interesting and valuable fringe, hobbyist, and obscure niche forums having been banned or moderated into inane milquetoast. Now, its value seems primarily as a customer support resource for companies outside the US, or as a platform for attracting clicks on other platforms.

Reddit's going the way of MySpace. Unless you like burning money, this IPO is one to skip. All the things that made Reddit great, once, are gone now. There are no compelling reasons to use it; it's slow, intrusive, disrespectful to user privacy, performatively moralizing and preachy, caters to the worst sort of moderation and curation power dynamics, and serves no relevant purpose in the ecosystem of the modern internet. The best and only value of Reddit comes from older archives of scraped content now used as training data for AI.