catalina.out is the redirected stdout and sterr files for Tomcat. If it's approaching 1GB, then either something is very, very wrong with Tomcat, or webapps are logging to stdout - or worse, using System.out.println/System.err.println. Webapps should not log to catalina.out, regardless of how convenient it might seem. Aside from exploding Tomcat's log file size and making it harder to find what you want, there's a potential security issue.. Not every wite likes the idea of application programmers debugging with the unrestricted assistance of system logfiles.
You can build a custom Tomcat that will log to a rotating file, but since rotation involves closing the old file and creating/writing a new one and that's not really something you can do with stdout and stderr, the vanilla distro can only rotate when Tomcat stops and restarts. Which it will do, so forcibly deleting catalina.out means throwing away potentially important log history.
If you do delete catalina.out while Tomcat is running - and I don't think that Windows file locking permits that, so let's talk Linux/Unix: In that case, the file directory entry will be erases, but Tomcat will continue writing to the deleted file, since In Unix-like systems, the directory entries are more abstract than they are in Windows. Meaning that potentially the disk could fill up and there wouldn't be any obvious reason why. Only after Tomcat was stopped would the space become avaialble. And in such a case, the reason Tomcat "stopped" miight well be that the whole OS crashed.
So try and keep extraneous chaff out of catalina.out and maybe do regularly rescheduled restarts of Tomcat. If there's that much to write about, there may be other JVM resources that need a break as well.
"privilege" comes from the Latin words for "private" and "law" (legal) and dates to feudal times. To "claim privilege" meant that you were above the laws that applied to the common people.
I've got no option but to sell you all for scientific experiments. Or a tiny ad: