This operation can be performed only by users assigned the Admin role.
To restrict withdrawal of a specific asset, proceed as follows:
Navigate to Settings > Assets in the Admin Panel main menu.
Locate a required asset in the list. You can use the search panel displayed at the top of the screen to find the asset in question (for example, BTC).
Select a list entry corresponding to the specified market and click the gear icon displayed on the right side of the row.
In the dialog window that is invoked, disable the Can Withdraw option.
Click Proceed to apply the changes and close the dialog window.