Unable to remove MariaDB persistent storage with Docker Rootless - mysql

Question

I am using Docker as Rootless. I dedicated the user gcadmin (UID 1001) to control the docker containers.
One of my container is running a mariaDB image.
I have configured a docker volume to get persistent storage in my docker-compose.yml file :
volumes:
...
./docker_volumes/mysql/data:/var/lib/mysql:rw
...
On first container startup, my data folder is created and populated using the user mysql (UID 999) :
// From within the container
root#f7e3b6722b0b:/var/lib/mysql# ls -la
drwxr-xr-x 6 mysql mysql 4096 Jul 25 15:44 .
drwxr-xr-x 1 root root 4096 Jun 7 02:44 ..
-rw-rw---- 1 mysql mysql 18309120 Jul 25 14:59 aria_log.00000001
-rw-rw---- 1 mysql mysql 52 Jul 25 14:55 aria_log_control
On host side, the files appears as owned by UID 166534 :
gcadmin#host:~$ ls -la docker_volumes/mysql/data/
drwxr-xr-x 6 166534 166534 4096 juil. 25 15:44 .
drwxrwxr-x 5 gcadmin gcadmin 4096 juil. 25 14:51 ..
-rw-rw---- 1 166534 166534 18309120 juil. 25 14:59 aria_log.00000001
-rw-rw---- 1 166534 166534 52 juil. 25 14:55 aria_log_control
...
I understand that the 166534 come from userspace remapping : 165536 + 999 - 1 = 166534
gcadmin#host:~$ cat /etc/subuid
gcadmin:165536:65536
...
Now I want "gcadmin" to be able to remove the docker_volumes/mysql/data/ folder to reset MariaDB to its initial state.
gcadmin#host:~$ rm -rf docker_volumes/mysql/data/
rm: Unable to remove 'docker_volumes/mysql/data/multi-master.info': Permission denied
...
Of course gcadmin doesn't own the files and I get a permission error.
In my use case, "gcadmin" can't have root privileges for security reasons.
How can I remove the peristent data folder of MariaDB without having root privileges on host side ?