Get hold of a Win98 boot disk from bootdisc.com click here, save it to floppy and boot to a DOS prompt. Navigate to the offending files and delete them. If they are long filenames you will either need to enclose the entire filename within quotes (e.g. del "thisisthelongfilename.???" ) OR use the tilde ( ~ ) as is is shown in the DOS listing of the files.
To move to the folder from A:\ type C: [return]
to move to the folder from c: type cd foldername [return]
If they are in C:\folder1\folder2\folder3 navigate by typing cd folder1\folder2\folder3 then use the del command followed by the filename as above.