The command added a line to the end of your profile, which is a hidden file in your home directory. If you hadn't done anything previously to create a profile, it made a new file containing just this one line.

You can edit your .profile file to remove the new line, but if it only has that one line, you can delete it entirely by opening a terminal and typing:

To check the contents of the file before deleting it, enter:

If you need to edit it to remove just this one line, you can use vi. The arrow keys move the cursor to the line you want to edit, then just type dd to delete the line, and :wq to enter command mode, write the file, and quit the editor.

Vi doesn't use the return key and the dd won't show up on the screen anyway so these commands are shown on separate lines above just for clarity. If you make a mistake, :q! will exit vi without saving and if you get into a mode where those commands don't seem to work, press the Esc key on the virtual keyboard to get back to the normal mode.

Good luck!