it seems /usr/src (apparently old kernels) used up all my inodes

Dateisystem Inodes IBenutzt IFrei IUse% Eingehängt auf /dev/sda4 489600 489600 0 100% / devtmpfs 219658 539 219119 1% /dev none 219844 474 219370 1% /run none 219844 3 219841 1% /run/lock none 219844 8 219836 1% /run/shm /dev/sda6 5963776 8361 5955415 1% /home

tried everything to remove/purge etc. the old kernels, without success.. dpkg is not working anymore, tried a few manual commands but 12.04 gives me nothing. apt-get etc. is not possible due to lack of space on the hard drive...which is not the problem obviously. however cannot install/ remove anything! read a lot about users with the same problem, but their solutions are not working for me. Anyone out there who could help? thanks a lot!