Reclaim the storage for “others” on my iPhone 6

The “others” takes over 8 G space on my 16G iPhone 6 storage. I want to get rid of it through reset and restore from iCloud’s daily backup. Btw, since my Pc and Mac are both old and could not upgrade to iOS 11 and above any more. They both could not recognize my iPhone 6. So the reset and restore to me is the only option now. Can someone direct me to the right resources ? Since I never done this before. Thanks Roland