I created an account for my uncle's iPhone, he used the phone for 4-5 months and asked me the password but I forgot it completely and don't either remember its google password or security answers, he had already tried many passwords on the phone and the iCloud is now locked, how can I unlock it? is there a way to unlock it through phone number?
Apple has a variety of options depending on what status your account is on their servers.
- Gain control of Apple ID (which is used to identify the iCloud account)
Apple.com/support can determine what's the status - keep in mind, they don't disclose some things by policy since people try to hack into other people's accounts - so you will need to jump through the hoops they set out for you or abandon the account.
Start here for the first advice on what to do in case it's a simple unlock request like you mentioned where it uses an emergency contact number or email account to verify you are in control of the details that were set up when the account was created.