This method supported all idevices and ios 9 to 13.6
Instruction:
1. Unplug simcard / turn off bluetooth of iphone and turn off bluetooth all near idevices
2. Turn ON WIFI ( but don't input passsword ) => Choose wifi name => click "i" choose Proxy http => choose Manual => Server: x.x.x.x => Port: xxxx => Save
3. Comeback to name WIFI u already setup proxy before => input password
4. Open safari => input: x.x.x.x:xxxx => click fiddler certification => choose install profiles
5. Settings => General => choose Profiles => choose " Do_Not_Trust_FidderRoot" click " install " => click DONE
6. Settings => General => choose About => choose Certificate Trust Setting => choose " Do_not_trust_fiddlerRoot" and click ON
7/ Setting => choose Apple ID => choose iCloud
=> If u see display Unable Storage => can not removal icloud
=> If u see display Storage iCloud => mean u can removed OFF