How can I remove iCloud from my phone without password??

The password for Apple ID is always required when Apple ID is signed out ( to remove the account ) from iPhone Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac - Apple Support

So to be on safer side before signing out , make sure you have all credentials for the account , even the password .

See If you forgot your Apple ID password - Apple Support

By the way how is account set with secondary authentication or two factor authentication .