Step 1 First navigate to the Add Label dialog box with the instructions depending on the mode of the page.

Step 2 Focus on the Add Label edit text box. Then press Tab twice to land on the labels added. By hitting Tab you can navigate among the labels for the page. 

Step 3 Next to each label there will be a tab-able item named as "Delete Label" or reads press shift + enter to delete label. Press Shift + Enter on it if you need to delete the label. 

Step 4 Once you delete the label you will loose focus then press Insert + Ctrl + E to find the Add Label edit box to get the focus back to the dialog box.  

Step 5 Press Escape to exit the Add Label dialog box.

Note If you are in the view mode of a page Pressing Insert + 3 and then pressing l will bring the Add Label dialog mentioned in Step 2. In view mode of the page use Enter instead of Shift + Enter to delete a label in regards to Step 3.