Add or delete buttoms from the Atto HTML editor in Moodle

You need to go to Settings > Site administration > Plugins > Text editors > Manage editors. There you can choose the editor plugins you wish to use and arrange them in order.

If you want to add or delete buttons in lets say the "Atto HTML" editor you will need to do the following:

Click in settings to edit them:

Consider that...

 The configuration consists of groups (one per line) followed by the ordered list of plugins for that group. The group is separated from the plugins with an equals sign and the plugins are separated with commas. The group names must be unique and should indicate what the buttons have in common. Button and group names should not be repeated and may only contain alphanumeric characters.

According to the above you will be able to add or delete button by adding the button name in the correct group.

For example, if we want to add the noautolink button we will need to add the word "noautolink" to the list as bellow...

1.  Noautolink button not showing in the editor

Editor view as below.

2. Add the word "noautolink":

The button is now showing in the editor:

I got inspiration for this article here