c:\tmp>set DEMO=C:\perls\strawberry-perl-5.32.1.1-64bit-portable\perl\site\bin;

c:\tmp>set DEMO=%DEMO:C:\perls\=DISABLED%

c:\tmp>echo %DEMO%
DISABLEDstrawberry-perl-5.32.1.1-64bit-portable\perl\site\bin;