How to delete a misnamed file on Android?

I’ve a file called like t0.t1 t2 t3 on my Android Device.

first it had a bad name from download and I tried to rename it. Something has to gone wrong. It was o1.o2 before.

I tried to rename it to something else - only o2 should be the same and t0-t3 the name before the file ending

Now the name is like above, but without file ending.

RootExplorer shows me the file like above (first line)

the custom ROM file explorer .o2.

I cannot rename, move or delete it.

Any ideas?