I need to free up space on my wr-740, which packages I can uninstall without causing a problem and without having to generate new firmware.
@irmaox, welcome to the communnity.
I know this may sound strange; but - it's not possible to remove packages from a firmware to [re]claim space. This is because the act of deleting a file on flash space - merely adds a placeholder to remind the system that the file is deleted. A reset to factory defaults will find the packages replaced.
You must compile a firmware, minus the packages to save space.
@lleachii beat me to it! Everything he said is right.
If you have installed packages that were not included in the original ROM using the opkg install system, you can remove them to free up space.
opkg remove <package_name>
But to reiterate, this only works for user-installed packages not included in the image you used to flash OpenWrt onto the router.
Or you can use the image builder to build your custom image from prebuilt packages...
it's possible make upload of older version than installed?
"[Any older version] is not recommended for any use at this time due to multiple, severe, well-known, actively exploited security vulnerabilities in its kernel, third-party applications, and 802.11 protocols."