Many websites don't like having the blue outline on their actionable elements because it doesn't look good, but when someone tabs through it's difficult to know which item is currently focused. Combined with little to no labelling, someone who depends on accessibility features won't be able to use your website.
With CSS you can modify the look and feel of the outline shown when an actionable element is in focus.
Seeing an element's outline is an important accessibility feature that we, as developers, shouldn't remove.
If you really don't want to use outlines, replace it with some other style that makes it obvious that an actionable element is currently in focus.