By default, ruler guides are light blue, and can be hidden from the view menu or using the keyboard shortcut Ctrl + semicolon .
Also by default, bounding box edges on layer 1 are blue. Hide those using Ctrl + H.
You can hide anything non-printing buy going into preview mode. Hit W if there is no active text cursor, or use the view menu or the button at the bottom of the toolbox. Preview mode has three states: Page only, bleed area, or bleed plus slug area.
You can clear an individual guide by selecting it and hitting backspace or delete, or shift clicking or marqueeing a group of guides if you want to do several. Clear all guides, and this is going to seem strange, using Layout > Create guides ... and leaving the horizontal and vertical number fields at zero, then check the clear existing guides box.