Hello, so Ive bought new bigger frame but due to my inexperience I got myself 15mm dropout which mean Im unable to put on my rear wheel since i have 10mm male axle. When it comes to new rear hub im not the biggest fan of it since I would have to buy it and that would be expensive. So I want to ask if there is a option on swapping my sealed-bearing cassette, 3/8 in axle to either female or trough axle and if it is possible (only in the last option) make one. Thank you
Really the only way to do it is to buy a wheel or hub that fits the frame. You can get ok quality rear wheels for around $120 from Rant or a complete wheelset from Fit for $160. Walmart bikes sometimes come with spacers for 3/8 axles to fit 14mm dropouts you could check around for a pair of those if you're really wanting to use your 3/8 wheel. There are probably hubs out there that can be swapped to a female axle but you will still have a 3/8 axle since most 14mm axle bearings won't fit the hub shell.