I am running out of space and when I checked, I found that I have
# pwd /usr # ls -l .sujournal -r-------- 1 root wheel 33554432 Dec 31 1969 .sujournal
I wanted to ask should/can I remove it? Any implications of that?
As a general rule, if you see a system file and you don't know what it is, don't remove it. Even more generally, if an action requires root permissions and you don't know what it would mean, don't do it.
.sujournal file contains the soft updates journal. The file is not accessed directly as a file; rather, it's space that is reserved for internal use by the filesystem driver. This space is marked as occupied in a file for compatibility with older versions of the filesystem driver: if you mount that filesystem with an FFS driver that supports journaled soft updates, then the driver uses that space to store the SU journal; if you mount that filesystem with an older FFS driver, the file is left untouched and the driver performs an fsck upon mounting instead of replaying the journal.