Sometimes when a storage device (i.e. SSD or HDD) has been used for a previous vSAN deployment or has other leftovers it cannot be re-used (either for vSAN or a local VMFS datastore) right away. When you try to format the drive as shown below the error message “Cannot change the host configuration”:
The easiest way is to change the partition scheme from GPT to MSDOS via CLI (and back via GUI) and has been described in the community before.
However, even that may fail, e.g. because of the error “Read-only file system during write”. This can occur if the ESXi hypervisor finds traces of old vSAN deployments on the drive and refuses to overwrite these. In that case you first have to delete those traces manually. Log into the host in question as the root user and issue the vSAN commands needed. For deleting a SSD the command looks like this:
vsan storage remove -s naa.6006016045502500c20a2b3ccecfe011
Afterwards repeat the steps described in the link above to correctly (re)claim the entire diskspace and then use it according to your plan.