If you've setup a buy instruction and you want to cancel it, you need to navigate to the Pending Instructions page, which you can do by clicking on the "Pending Instructions" menu item as highlighted in yellow in the image below.
Clicking on that menu option will take you to the instruction overview page, as shown in the image below, where all your Pending Buy instructions will be displayed.
To cancel the instruction, click on the little red cog icon in the top right hand corner of the instrument you want to cancel. Doing so will give you the option to Cancel the buy instruction on that instrument - by clicking on the word "Cancel" as highlighted in the image below
Clicking on cancel, will change the contents of the cell and ask you whether you are sure you want to cancel the pending instruction - as shown in the image below.
Clicking "Yes" to confirm the cancellation, will give you a message saying "Successfully cancelled your instruction" - as in the image below.
If you don't know what a Buy Instruction is, or how to create one - visit our detailed FAQ article What is a buy instruction and how does it work?