API users are added to Roles where the System Manager can control the access that an API user has

Top Menu >> Setup >> API 

From the Setup page (right side) click API. 

Click + Add an API User.

Select a Role for the user. 

Note: We recommend creating a new staff role for the API user and granting it only certain privileges.

Give the User a Name and then select Finish.

After the user is created an API key will be generated.