From:
https://www.thedrive.com/the-war-zon...last-two-years
Until 2016, there was a legal requirement to keep the F-117s in so-called "Type 1000" storage, meaning that they would be maintained in a state where they could be returned to active service relatively quickly, if necessary. The annual defense policy bill, or National Defense Authorization Act, for the 2017 Fiscal Year nullified this and replaced it with the four-per-year disposal plan. The Air Force Life Cycle Management Center at Wright Patterson Air Force Base in Ohio subsequently developed what it calls a "migration plan" for how to get rid of the F-117s.
I have no idea how accurate that is. If you google for the Act mentioned it doesn't seem to say 4 a year anywhere
https://www.congress.gov/114/crpt/hr...114hrpt840.pdf