Hi @tranuyen333 ,
Welcome to TPG community!
You may email our team to add an Authorized User in the account. Send the complete name of the user including your account details. firstname.lastname@example.org
In doing so, you authorise this person to contact TPG on your behalf and you authorise TPG to discuss with them/him/her any billing, contract, technical or other information pertaining to your account including making any changes on the account except adding or removing another authorised contact person and canceling the account.
Let us know should you require further assistance.