Uh... well... yes...
Theoretically it is possible, but that involves installing tools that modify your partition table, resize filesystems and some stuff more. Not a procedure I'd recommend (I'm not even sure which tools to use) to a newbie.
Instead, I'd suggest your backup your /home directory, and them remove the line in /etc/fstab about /home and reboot. This will not mount you 100Mb /home partition, and as a result /home will now live in your 74Gb root partition.
After this procedure, /home will start out empty (because the 100Mb partition isn't mounted), so you have to restore your backup.
If you want to put the 100Mb to some use, you can mount it somewhere else, or maybe turn it into an extra swap partition.
Alternatively, I recommend a reinstall.