How to delete a file with invalid characters in Windows 8.1 (not even Cygwin helps)

After a problem I've encountered with the Windows 8 Store I had to delete a system folder.

Unfortunately, inside it there's a file with invalid characters (filename as it's displayed via ls or dir):

0-FileAssociation-https∺∯∯next-services.apps.microsoft.com∯search∯6.3.9600-0∯776∯en-US_en-US.en.el∯m∯US∯c∯US∯il∯en-US∯cp∯10005001∯FileAssociation∯cid∯0∯pf∯1∯pc∯0∯pt∯x64∯af∯0∯lf∯1∯s∯0∯2∯pn∯0.dat

Edit: In windows it appears as

0-FileAssociation-https???next-services.apps.microsoft.com?search?6.3.9600-0?77‌​6?en-US_en-US.en.el?m?US?c?US?il?en-US?cp?10005001?FileAssociation?cid?0?pf?1?pc?‌​0?pt?x64?af?0?lf?1?s?0?2?pn?0?pgc?-1?phrase=sec.dat

It's located at in a rather long path:

C:\Users\Kostas\AppData\Local\Packages\winstore_cw5n1h2txyewy\LocalState\OldCache\0

What I have already tried without success:

• renaming it via either File Explorer -pressing F2 doesn't work and rightclicking doesn't show the full shell extension menu (shows only the entries Open with and Send to, instead)-
• renaming it via elevated cmd
• deleting via File Explorer
• starting elevated cmd and trying the del command
• launching Cygwin as admin and trying

1. rm -rf *.dat 2. mv *.dat 1 3. find . -type f -delete 4. rm -- *

and: 5. set -- 0-FileAssociation-https* echo "${#} file(s) found" (provided that the above outputs "1 file(s) found") rm -i 0-FileAssociation-https*
All the above commands give: "cannot stat/remove/delete: No such file or directory"

The solution:

• go to task manager and kill explorer.exe
• go to File>Run new task: cmd
• navigate to the OP path
• use the del command
• then re-launch explorer.

Credit goes to user illuminÉ.