Also see If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled https://support.apple.com/en-us/HT204306, especially the section entitled Remove your passcode.
If you don't have a computer as mentioned in Remove your passcode, then "borrow one from a friend, or go to an Apple Retail Store or Apple Authorized Service Provider." Of course the last option usually is not available now.
Later the document says: "If you can't update or restore your device using recovery mode, or you can't use recovery mode because of broken or stuck buttons, contact Apple Support. Then follow the steps to set up service for your iPhone, iPad, or iPod touch."
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And see Turn off Activation Lock https://support.apple.com/en-us/HT201441See this heading If you erased your own device.It says: "If you don't sign out of iCloud before you put your device in recovery mode and restore, it might remain in Activation Lock. That means you need to enter the same Apple ID and password that … was used when … [the device was last set up]. You might need to use: If you forgot your Apple ID https://support.apple.com/en-us/HT201354; If you forgot your Apple ID password https://support.apple.com/en-us/HT201487; and If you forgot the answers to your Apple ID security questions https://support.apple.com/en-us/HT201485. Post back if you have trouble removing activation lock.
