Removing terminal special character `^@`

when I less a file, it looks like this.

^@00002201-271f-43b9-81a7-000b0a31abe5
^@00004695-2281-44df-b18d-bd68b63fced4
^@00009273-3a0f-4c2e-b708-805e02147f55
^@0000a0e6-3889-43f2-9635-63e114c38f29
^@0000a386-cf2f-4459-bd63-e83fb144013c

The problem is ^@. When cat this file, that character is not seen.

What is that character? And How can I trim that (in C or awk whatever)?