If it’s the inside you want to clean, then get quality leathers, I can take the whole liner out of mine, which is fitted with zips & velcro. Just pop in washing machine
Most leathers are happy to go through a low temp wash cycle, slow spin. Best done in a laundrette washer !!! Let drip dry & wear them before fully dry to make it fit like a glove. Use a leather lube/oil once fully dry. To protect it & keep it supple.