How do I remove the activation lock off of my iPhone 15 pro max ?

See the following Apple Support article for information on removing Activation Lock: How to remove Activation Lock - Apple Support

Note that you will need the Apple ID and password that was used to lock it.

Depends on the history of the device:

• If you purchased it from Apple or Authorized Apple seller and have the receipt, Apple will unlock it for you. You can use the link provided by FoxFifth. They do not get involved in third party sales, so if purchased elsewhere you may find they will not help.
• If this is a used device that you purchased, you should return it if you have that option.
• If you are able to contact the original owner, they can remove the device from their account.
• If you are unable to contact the original owner and cannot return it, then you will most likely never be able to use the device. Activation Lock is a theft deterrent that will prevent a device from being used if it was stolen from you.