what is your basis for the EAD and what is your current status? If EB 485 principal, not doing a job (as H4) may have a risk of 485 denial. If EAD is for OPT and non-485 related, yes you can change to H4. If EAD based on I-485 as US citizen's spouse, your no longer a US citizen's spouse kill your 485 chance (and EAD is also canceled).