You can delete a goal (without closing your entire Endowus account) by following these steps:
Redeem the entire investment portfolio for the Goal: You can do this by selecting the goal on the left hand panel> Select Manage goal > Select Redeem > Select Redeem all
After the entire investment value for the Goal has been redeemed, you go back to the dashboard and select the goal on the left hand panel> Select Manage goal > Select Delete Goal
Please note that you can only delete goals which do not have any pending and/or processing transactions, and do not have any investment value.