you mean "center", not "origin".

bring the 6 to the right of the equation to get -6.

to complete the square for the x's, you need to add 4 to both sides

to complete the square for the y's, you need to add 9 to both sides

to complete the square for the z's, you need to add 1 to both sides

thus the right side becomes -6 + 4 + 9 + 1 = 8 which is the square of the radius. hence the radius is

(Look up how to complete the square)