In order to close your TRX supply on JustLend DAO, you will need to initiate a withdrawal request. This can be done by logging into your JustLend DAO account and navigating to the 'Withdraw' page. From there, you will be able to enter the amount of TRX you wish to withdraw and submit the request. Once the request is approved, the TRX will be removed from your supply and the withdrawal will be completed.