DEEX, BTS and some other tokens are native, so they cannot (more precisely, cannot) be removed from this blockchain, they can only be transferred to other accounts. Therefore, the "withdraw" button is not available for these tokens, although this does not prevent at all, for example, getting BTS tokens to your Binance account or DEEX tokens to your BTC-alpha account. Only the "Transfer" button will be available for these tokens. Those. it's just a question of the correctness of the terminology.
Also, the "withdraw" button will be unavailable for other tokens, if the possibility of their withdrawal is provided, but at the moment the user’s balance is "zero" - the button appears only if the user is logged in (the lock at the top right is open) and the token balance is more than zero.
Example: to transfer BTS tokens to the Binance exchange from the Deex exchange, you need to get the account name and memo in the Binance account, then enter this data in the Deex exchange wallet by selecting the "Send" arrow opposite the BTS asset ( output will not be there). After sending the funds are credited to the specified Binance account, their system identifies you by the specified note (memo) and you are already charged to your balance on the Binance exchange. A similar operation is performed when transferring DEEX tokens to the btc-alpha exchange: the "Send" function, the account name, a note.