Hello Leonardolemos,
Thanks for choosing the Apple Support Communities. If your Mac is Activation Locked to another person, you'd want to follow these steps to attempt to have it removed.
How to remove Activation Lock - Apple Support
"Remove Activation Lock on the device
Follow the onscreen steps to enter the Apple ID and password you used to set up your device or your device passcode.
Learn how to find your Apple ID or reset your Apple ID password.
Remove Activation Lock on the web if a device is offline
- Go to www.iCloud.com/find.
- Sign in with your Apple ID and password.
- At the top, click All Devices.
- Select the device that you want to remove from iCloud.
- Click Remove from Account.
Start a support request
If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request."
Cheers!