Are you looking for a Sales Demo for L100 Payroll training in version 23.207.0025?

Even the training is only using version L100_23_200_0151…  And the Sales Demo only goes up to: 

  SalesDemo_23_206_0006

yes and I think 23_206_0006 is the latest for practice demo.

so another question is like, is there any way we can downgrade instance version 23_207-0025 back to 23_206_0006 ?

If you have a backup of the database you can restore the backup, and reinstall the application back to build 206.  If not, you’ll need to rebuild your demo environment as you can’t “Downgrade” your instance after upgrading.