I installed aaPanel latest version to CentOS 7.9 with 15G disk.
Right after LEMP installation it just took all the free space, specifically /www folder took 9.6G

[root@aapanel ~]# df -h
Filesystem                       Size  Used Avail Use% Mounted on
devtmpfs                         452M     0  452M   0% /dev
tmpfs                            464M  8.0K  464M   1% /dev/shm
tmpfs                            464M  6.2M  457M   2% /run
tmpfs                            464M     0  464M   0% /sys/fs/cgroup
/dev/mapper/centos_aapanel-root   13G   13G   24M 100% /
/dev/sda2                       1014M  163M  852M  16% /boot
/dev/sda1                        200M   12M  189M   6% /boot/efi
tmpfs                             93M     0   93M   0% /run/user/0

[root@aapanel /]# du --max-depth=1 -h /www
9.5G	/www/server
0	/www/wwwroot
0	/www/wwwlogs
12M	/www/backup
0	/www/.Recycle_bin
9.6G	/www

[root@aapanel /]# du --max-depth=2 -h /www/server/
286M	/www/server/panel/pyenv
132K	/www/server/panel/logs
44K	/www/server/panel/vhost
104K	/www/server/panel/install
0	/www/server/panel/plugin
56K	/www/server/panel/config
116K	/www/server/panel/script
168K	/www/server/panel/rewrite
356K	/www/server/panel/data
16M	/www/server/panel/BTPanel
6.8M	/www/server/panel/class
20K	/www/server/panel/ssl
40K	/www/server/panel/__pycache__
0	/www/server/panel/tmp
309M	/www/server/panel
4.0K	/www/server/stop
0	/www/server/nodejs/vhost
0	/www/server/nodejs
75M	/www/server/php/74
75M	/www/server/php
477M	/www/server/nginx/src
12M	/www/server/nginx/sbin
196K	/www/server/nginx/conf
8.0K	/www/server/nginx/logs
8.0K	/www/server/nginx/html
0	/www/server/nginx/proxy_temp_dir
0	/www/server/nginx/proxy_cache_dir
0	/www/server/nginx/client_body_temp
0	/www/server/nginx/fastcgi_temp
0	/www/server/nginx/uwsgi_temp
0	/www/server/nginx/scgi_temp
489M	/www/server/nginx
8.6G	/www/server/mysql/src
8.6G	/www/server/mysql
76K	/www/server/pure-ftpd/bin
332K	/www/server/pure-ftpd/sbin
216K	/www/server/pure-ftpd/share
12K	/www/server/pure-ftpd/etc
644K	/www/server/pure-ftpd
53M	/www/server/phpmyadmin/phpmyadmin_a17446c367ad0ba3
53M	/www/server/phpmyadmin
9.5G	/www/server/

As you can see most of the space is taken by mysql/src folder.

Why it's not removed?
Why it's used during installation because I selected fast (rpm) installation?
Can I safely remove all /src folders?