First, we can check old logs and their size:

/var/log/ – a standard place for system logs, and applications, if not set otherwise. Using: ls -alh we can list all files with their size and du -h we can see the size of folders. Sometimes we do not need some archived old logs, so they can be deleted, but only if we are sure that they won't be needed anymore. 

In /var/log/  there are some folders, which can store a big amount of logs, e.g: /var/log/http/ which is standard web server (in most cases the apache web server) logs location. In our example the folder contains a lot of old logs (those are the ones with date appended in the end of file name) with size of a few gigabytes and those can be deleted, if we are sure, that they will be no longer required:

-rw-r--r--. 1 root root 34M Jun 22 10:06 access_log
-rw-r--r--. 1 root root 263M Jun 14 03:28 access_log-20200614
-rw-r--r--. 1 root root 301M Jun 21 03:35 access_log-20200621
-rw-r--r--. 1 root root 29K Jun 22 10:00 error_log
-rw-r--r--. 1 root root 323K Jun 14 03:28 error_log-20200614
-rw-r--r--. 1 root root 339K Jun 21 03:34 error_log-20200621
-rw-r--r--. 1 root root 1021M Jun 22 10:06 ssl_access_log
-rw-r--r--. 1 root root 6.8G Jun 14 07:29 ssl_access_log-20200614
-rw-r--r--. 1 root root 7.4G Jun 21 06:39 ssl_access_log-20200621
-rw-r--r--. 1 root root 51K Jun 22 10:00 ssl_error_log
-rw-r--r--. 1 root root 260K Jun 14 00:10 ssl_error_log-20200614
-rw-r--r--. 1 root root 252K Jun 21 02:26 ssl_error_log-20200621
-rw-r--r--. 1 root root 1.2G Jun 22 10:06 ssl_request_log
-rw-r--r--. 1 root root 7.7G Jun 14 07:29 ssl_request_log-20200614
-rw-r--r--. 1 root root 8.5G Jun 21 06:39 ssl_request_log-20200621

/servers/(cat/spell/pm)/logs  is the location of xtm application logs, or corresponding localization on your server, depending on your settings used at the installation. Here we can also see files with appended a date at the end of file, and those, as explained above, can be deleted, if no more required:

-rw-r-----. 1 xtm xtm 15M Jun 15 05:45 catalina.out-20200615.gz
-rw-r-----. 1 xtm xtm 15M Jun 16 04:20 catalina.out-20200616.gz
-rw-r-----. 1 xtm xtm 14M Jun 17 05:17 catalina.out-20200617.gz
-rw-r-----. 1 xtm xtm 15M Jun 18 04:58 catalina.out-20200618.gz
-rw-r-----. 1 xtm xtm 20M Jun 19 06:43 catalina.out-20200619.gz
-rw-r-----. 1 xtm xtm 18M Jun 20 08:06 catalina.out-20200620.gz
-rw-r-----. 1 xtm xtm 16M Jun 21 05:56 catalina.out-20200621.gz 

Second, we move to xtm files:

We can check and delete files in temporary catalogs, in case they weren't cleared automatically. There are many ways to do it, but most efficient is to use a bash script and modify it to your needs. A good example of such script is the one below:

find /xtm/webapps/generatedfiles -mindepth 1 -mtime +30 -delete > /dev/null 2>&1
find /xtm/xtm/temp -mindepth 1 -mtime +30 -delete > /dev/null 2>&1
find /xtm/xtm/nlpservice -mtime +7 -delete > /dev/null 2>&1
find /xtm/xtm/data/ -maxdepth 2 -name Download |xargs -n 1 -I D find D -ctime +7 -delete
find /xtm/xtm/data/ -maxdepth 2 -name temp |xargs -n 1 -I D find D -ctime +7 -delete
find /servers/cat/temp -mindepth 1 -mtime +1 -delete
find /servers/pm/temp -mindepth 1 -mtime +1 -delete
find /servers/spell/temp -mindepth 1 -mtime +1 -delete

Please bear in mind, that the paths shown above are the standard installation paths of xtm app, if you have different ones, then edit it accordingly!

To create such a file, please do as follows:
From the console:  create a bash script and make it executable:

vi // inside the program press "i" and then paste the above content into the file, then press "esc" and " :wq " to save and quit
chmod +x

Lastly, we can delete archived or unused projects (do it only when You are sure that you will never ever need them again – the process of deleting projects is irreversible!)

Go to /xtm/xtm/deleted/ or /xtm/xtm/archived (in case You have some non-standard installation path, go according to your installation paths)
Inside this folder(s) you can find the IDs of projects that have been either deleted or archived, and you can choose which one you can delete if any.

If You ever made some database dumps, there is a possibility, that they weren't deleted after dump/or restore. 

First, check your bash history to find out if some hints are there:
In the console, please use: history | grep -i pg_dump – this command will show the bash history narrowed down to pg_dump command. You can then check the corresponding folder where the dump was put into, and delete it if needed. In case there is no pg_dump in bash history, you can always check /servers/files/ if there are some leftover unneeded files.