Yes, You can change the IP address of your Proxmox host. You will need to make sure that the /etc/hosts file is updated to be correct, also you will need to modify your /etc/pve/corosync.conf (possibly) to reflect this change as well.
The /etc/pve directory is managed via the corosync process. It is important that in order to change any file within this directory that you need to run as root from the command line:
# pvecm expect 1 (this allows you to edit the file).
Also note that if you do update the corosync file with any IP changes, that you need to *update* the config_version number under totem section otherwise you will have issues.
Once you make the changes go ahead and restart the host. You will need to run this same process on the other hosts as well.
