Should you wish to delete your Decathlon Account you simply need to follow the below steps.
Log into your Decathlon.ie account and select the "Account" tab in the top right of the page followed by "My Sports Profile"
You will now be asked to re-enter your login details and once complete you will now access your full Decathlon sports profile.
If you scroll down you will see the "Security" tab on the left side, select this and then the option to "Delete my Account" will be available.
Now if you select "Delete" a page will load informing you of the reasons to retain your account, but should you wish to continue with deletion you simply need to select "Delete my Account" and your account deletion will be complete.