The button is there for me when using ProfitUI_CE. In the Character window with a merc summoned click the blue icon at the top of the Mercenary tab. Above the spell area that appears you should see the training button.
If this is still failing, you can delete eq2ui_mainhud_persona.xml from your ProfitUI_CE folder. This will return you to the default Character window.
Last edited by Darqwood : 05-06-2017 at 02:10 PM.