Update won't start cause of disk space

When you try to update, and you’ve got the error below (disk space critical):

DISK CRITICAL - free space: /boot 50 MB (37% inode=99%);| /boot=83MB;;91;0;141

You can cleanup old kernels with following command.
This will leave the current and the last current in place (count = 2)

package-cleanup --oldkernels --count=2