Ask your DM to find out who the buyer is, you can email them and ask for the sales data. Look specifically at the data for before the endcap and after.
Just because it isn't moving quickly doesn't mean it's not profitable. If it's a high margin item, a slight uptick in units may be enough to make the space worth it.
If sales remained largely flat, ask your DM to have it clearanced. If you want to be a prick, change your onhands up artificially to make auto replenishment stop, just remember to change it back before it clearances.
Another option is to ask your DM to significantly reduce the order to level (otl) to control shrink.