Method1:
get a command prompt as administrator in the directory with the file that has too long name
dir /X
this will tell you it’s shortened dos filename
then you can say
del shortr~1.txt
Method2:
use 7-Zip, you may have it installed already
it will complain that it cant’ send long file names to the recycle bin
hold down SHIFT while pressing DEL and it will delete permanently, bypassing the recycle.