I have many rows in mikrotik logs:
could not save configuration changes, not enough storage space available.
Files shows there are nothing to remove, used 16.0 MiB of 16.0 MiB, BUT I can make a backup, which has nearly 2MB.
I can donwload a new packages, which do not shows up in the Files, co I cannot delete them or anything else.
Appreciate any help.
Hi, welcome to the club 
.
Did you have the wireless package installed ?
Bad news: You need to reset all and netinstall - no other way that I found to fix it.
Good news: backup still work (without changes can’t be saved) and you should do before reset and netinstall.
Kim
Well, I thought someone would suggest me to make a netinstall 
But I could not boot this mikrotik device to netinstall mode or I am stupid.
I tried a milion times without any luck on two different laptops. I setup IP on laptop to 192.168.98.2. in netinstall boot I had 192.168.98.3. I holded a reset button until USR turn off (about 15 secs), but I cannot see anthing on netinstall. I tried to push button a litle longer, but no luck either.
Of course I disabled windows FW, Antivirus protection and used port no 1.
On RB951 I can go to netinstall mode without any troubles.
Did you have a console cable on it ?
I have done it without, just with a linux server
./netinstall-cli -r -a 192.168.88.3 routeros-7.17.2-arm.npk
...
You disconnect, press reset until USR get off and then wait looooooong time.
I already almost give up and went away to do other things … it took I think almost 30 min to install, So if you have no console cable, be very patient, all will go well
You are right, I have to wait a looooong time. Now I can try to make a clean netinstall.
Is it OK to make a binary backup before and restore it after netinstall ? Seems OK to me, I am asking to be sure.