How do you delete a column in TextEdit?
RTF table support is quite limited in TextEdit.

If the column you want to get rid of is not the last column in the table (in which case grgarside's answer above is your best option) you can try the procedure below:


Let's say you want to delete column "c" below:


Hold down Option to mark the contents of the column (note that the cursor changes shape to a cross):


Now you can either: 


Press Delete to delete its contents:


Position the cursor in every empty cell and press the fndelete key combination (you can also use the delete ⌦ key, but you will have to rearrange columns later):



until you have deleted all of them:




or:


Press Merge in Format > Table...:


Select the contents of the column and delete them by pressing Delete:


Place the cursor in the empty column and press the fndelete key combination (you can also use the delete ⌦ key, but you will have to rearrange columns later) to delete it.



I wish it were more straightforward, but unfortunately it isn't.