This part applies to reduction in grade and removal of employees covered by the provisions of this part based solely on performance at the unacceptable level. 5 U.S.C. 4305 authorizes the Office of Personnel Management to prescribe regulations to carry out the purposes of title 5, chapter 43, United States Code, including 5 U.S.C. 4303,which. (The provisions of 5 U.S.C. 7501 et seq., may also be used to reduce in grade or remove employees. See part 752 of this chapter.)