After I installed Openvpn and adblocker and upgraded the packages, my memory almost full, can you please recommend packages to remove which will not effect on security and privacy?
I am not a pro user and will not need pro utilities, I need security, privacy and no ads.
If you talk about flash (instead of RAM) memory, just note that you can't actually free the space taken by packages incluced in the flashed firmware. you can only effectively remove the packages that you installed by yourself.
I suggest you start learning how to use the Image Builder. This way you can exclude unnecessary packets and the ones you need take less space since they are compressed.
Upgrading or removing the packages already installed in the firmware actually decreases available space, because they're not deleted since they are in a read-only squashfs partition.