it is good to have a plan to mitigate the high interest rate.
but you do not need to have 0 debt to have peace of mind, to move into the next phase of life
Here's a quick financial awareness test. Which is better? (All other circumstances are identical, please note.)
1. $400,000 in your CPF Ordinary Account with a $350,000 mortgage balance at a 2.2% interest rate.
2. $50,000 in your CPF Ordinary Account with no mortgage.
If you picked Option 2, you're wrong.

Option 1 is increasing your wealth every month as long as the 2.2% interest rate (or some other comparatively low rate) endures. Or, in short, Option 1 is a money printing machine for you. Why would you ever want to turn off your money printing machine any earlier than required? You wouldn't/shouldn't, not if you're rational.
OK, here's another scenario:
1. $400,000 in your CPF OA with a $350,000 mortgage balance at 2.8%.
2. $50,000 in your CPF OA with no mortgage.
Which is better? THAT'S a more interesting question, but the correct answer is "not enough information." Suppose I told you that the owner of this home (and mortgage payer and CPF OA owner) has a terminal illness and the Home Protection Scheme (or other MRTA policy). Now the clearly correct answer is Option 1. That's because the HPS/MRTA will soon pay off the rest of the mortgage when the individual dies. Any/all accelerated repayment will be completely wasted, lost forever, so that'd be a terrible financial decision. Another possibility is that mortgage interest rates are headed down, and so the mortgagee rationally decides to ride out the 2.8% rate until he/she can reprice/refinance (perhaps for a fixed term of as many as 5 years) and get back into money printing mode. There are also some edge cases involving creditors/court judgments. CPF OA is protected against such risks, but home equity is not. So "it depends." The rate differential suggests accelerated repayment has some merit, but there are exceptions in this scenario.