The fact that you start your post with the word "Easy." leads me to suspect that you have not done this.
You’re forgetting the dodge congress used for many years, that as long as they pay what is owed to beneficiaries “that month”, as far as they are concerned, the program is solvent, even if it has a $25t *potential* debt.
As scurrilous as this is, it actually works, even at the low level. Your credit rating will be good even if you have a high debt, as long as you pay the interest on that debt on time.
So the way what I propose works is that you stop putting more people into the system, which will then slowly start to lower the potential debt. And you continue with the trick, paying beneficiaries what they are owed *that month*.
This means the cutback to government income comes from not being able to squander the FICA taxes immediately on receipt, as if the income tax was doubled. So yes, it will be an enormous hit to government revenues, but one they weren’t supposed to have in the first place.
The total hit to government revenue might be as much as 25-30% of the current budget, and that should be workable.