Hello if I’m already the executor of an estate do I need to still open a probate or can I just pay everything that needs to be paid?

A Will has no legal effect until a court admits it to probate (proving that it is the Will of the person who died.)  A person named as executor in a Will only becomes the executor when a court appoints him and issues Letters Testamentary, giving him legal authority over the deceased's property, authority to pay the bills as state law requires and to distribute what remains according to the Will.