Open terminal on your folder and write the command:
for i in ./*STRING-TO-REMOVE*;do mv -- "$i" "${i//STRING-TO-REMOVE/}";done
Replace STRING-TO-REMOVE to your string!
example:
list of files inside folder
file1-demo.pdf
file2-demo.pdf
file3-demo.pdf
file4-demo.pdf
[...]
i need to remove string "-demo" from filename
execute on terminal:
for i in ./*-demo*;do mv -- "$i" "${i//-demo/}";done
result:
file1.pdf
file2.pdf
file3.pdf
file4.pdf
[...]