If you want to know how to unlock the phone because you cannot remember the screen PIN, password, or pattern, it is best to look up the manufacturer’s guidelines for your particular mobile phone model. Android phones require different types of recovery procedures depending on the particular brand and model, so there is no point in looking for general information about bypassing locks on the internet. In case the phone needs a factory reset, which will erase all the local data on it, you should make sure that you still have another copy of that data either in the Google account or somewhere else. The reset process may also activate Android's Factory Reset Protection, which will require authentication of the previously connected account. If it is not your phone, just ask the owner to unlock it.