If you are no longer interested in an alert then it can be easily deleted.
Click on the drop-down menu button at the top right of the screen and then choose the My alerts option and then click on the Edit button. Select the X button next to the alerts that you wish to remove and the field will be emptied. When you have finished click the Save button.
If ever you want to use the alert again, simply return to the page and add it once more.