You can hide or show the Appsomnia icon on the dock. If you hide it you will only be able to access to the app from the top bar menu icon.
To hide dock icon, after opening Appsomnia app, click on the top bar icon and then click on the settings menu item.
Settings window will be opened. You can check the “Hide Appsomnia Icon on Dock” option to enable this feature or uncheck to disable.