In order to cancel the pending withdrawal you need to do the following:
Go to Account Payments there you can see Pending withdrawals, click on the one you wish to cancel "Cancel withdrawal".
Alternatively, go to Account Reports Funds history select the withdrawal you want to cancel tap "Cancel withdrawal".
On the main page of the platform click on Pending withdrawals, select the withdrawal you want to cancel and click on Cancel withdrawal.
Also, you can click on Deposit and pop-up will appear, suggesting to cancel the existing pending withdrawal.