[OnePlus 3 & 3T Cross Device Development] :
I don't know if it belongs here, but because I am on LOS IN just give it an try.

After several tastes of OS, I have the feeling there is a lot of stuff in my root directory which is not used anymore.

Here the ouput of ls -l:

total 5320
dr-xr-xr-x 4 root root 0 1971-01-29 22:22 acct
lrwxrwxrwx 1 root root 11 1970-01-01 02:00 bin -> /system/bin
lrwxrwxrwx 1 root root 50 1970-01-01 02:00 bugreports -> /data/user_de/0/com.android.shell/files/bugreports
drwxrwx--- 6 system cache 4096 1971-01-29 22:16 cache
lrwxrwxrwx 1 root root 13 1970-01-01 02:00 charger -> /sbin/charger
dr-xr-xr-x 2 root root 40 1970-01-01 02:00 config
lrwxrwxrwx 1 root root 17 1970-01-01 02:00 d -> /sys/kernel/debug
drwxrwx--x 46 system system 4096 2019-07-06 00:02 data
lrwxrwxrwx 1 root root 12 1970-01-01 02:00 default.prop -> prop.default
drwxr-xr-x 10 root root 3800 2019-07-06 20:42 dev
drwxr-xr-x 2 root root 140 2019-07-06 20:42 etc
-rw-r--r-- 1 root root 102640 1970-01-01 02:00 file_contexts
-rw-r--r-- 1 root root 1924384 1970-01-01 02:00 file_contexts.bin
-rwxr-x--- 1 root root 2348160 1970-01-01 02:00 init
-rwxr-x--- 1 root root 3080 1970-01-01 02:00 init.rc
-rwxr-x--- 1 root root 103 1970-01-01 02:00 init.recovery.hlthchrg.rc
-rwxr-x--- 1 root root 35 1970-01-01 02:00 init.recovery.mksh.rc
-rwxr-x--- 1 root root 5727 1970-01-01 02:00 init.recovery.qcom.rc
-rwxr-x--- 1 root root 111 1970-01-01 02:00 init.recovery.service.rc
-rwxr-x--- 1 root root 1323 1970-01-01 02:00 init.recovery.usb.rc
drwxr-xr-x 3 root root 60 1970-01-01 02:00 license
drwxr-xr-x 4 root system 80 1971-01-29 22:22 mnt
drwxr-xr-x 2 root root 200 1970-01-01 02:00 odm
drwxr-xr-x 2 root root 40 1970-01-01 02:00 oem
drwxrwx--x 21 root system 4096 2019-04-17 08:18 persist
-rw-r--r-- 1 root root 26662 1970-01-01 02:00 plat_file_contexts
-rw-r--r-- 1 root root 7212 1970-01-01 02:00 plat_hwservice_contexts
-rw-r--r-- 1 root root 9384 1970-01-01 02:00 plat_property_contexts
-rw-r--r-- 1 root root 1647 1970-01-01 02:00 plat_seapp_contexts
-rw-r--r-- 1 root root 16072 1970-01-01 02:00 plat_service_contexts
dr-xr-xr-x 392 root root 0 1970-01-01 02:00 proc
lrwxrwxrwx 1 root root 15 1970-01-01 02:00 product -> /system/product
-rw-r--r-- 1 root root 3807 1970-01-01 02:00 prop.default
drwxr-xr-x 3 root root 80 1970-01-01 02:00 res
drwx------ 2 root root 40 2019-06-30 18:53 root
drwxr-x--- 2 root root 6660 2019-07-06 20:42 sbin
drwxrwx--- 15 media_rw media_rw 4096 2019-07-06 09:59 sdcard
-rw-r--r-- 1 root root 811845 1970-01-01 02:00 sepolicy
drwxr-xr-x 2 root root 40 1971-01-29 22:22 sideload
drwxr-x--x 2 root root 40 1970-01-01 02:00 storage
dr-xr-xr-x 12 root root 0 1971-01-29 22:22 sys
drwxr-xr-x 19 root root 4096 2019-07-06 10:35 system
drwxrwxr-x 2 root shell 80 2019-07-06 20:42 tmp
drwxr-xr-x 5 root root 180 1970-01-01 02:00 twres
-rw-r--r-- 1 root root 5359 1970-01-01 02:00 ueventd.rc
drwxrwxrwx 2 root root 40 2019-07-06 20:42 usb_otg
drwxr-xr-x 3 root root 60 1970-01-01 02:00 vendor
-rw-r--r-- 1 root root 69361 1970-01-01 02:00 vendor_file_contexts
-rw-r--r-- 1 root root 8155 1970-01-01 02:00 vendor_hwservice_contexts
-rw-r--r-- 1 root root 15146 1970-01-01 02:00 vendor_property_contexts
-rw-r--r-- 1 root root 3126 1970-01-01 02:00 vendor_seapp_contexts
-rw-r--r-- 1 root root 1831 1970-01-01 02:00 vendor_service_contexts
-rw-r--r-- 1 root root 468 1970-01-01 02:00 vndservice_contexts

Could someone give me some input of stuff what really is not used in combination with LOS and can be removed? I know it is no big deal but I like a clean setup.