you'd better off modifying server roles, which was designed for security privileges. add sysadmin server role to your user. for better security you may have your custom server roles. but this approach will give you what you want for now.
- Object Explorer -> Server -> Security -> Logins
- Right click on your desired user
- Go to Server Roles on left hand side
- Make sure sysadmin is checked
- Hit OK and restart your SQL server
Good luck
