Clearing cookies in logout

[tommythejoat]

Our single sign on facility uses the organization membership system to log users into all the systems including vBulletin.

After a recent upgrade, we are having problems with the cookies that are used to transmit the user information between the systems with vBulletin. Specifically, I need to clear several cookies that were set initially by the membership system.

If they do not get cleared, there are problems trying to use that tool to log back in to vBulletin.

I tried using a plugin at the hook logout_process but this code appears to do nothing.

setcookie("bb_sessionhash", "", time() - 3600);
setcookie("iMISID", "", time() - 3600);
setcookie("iMISLogin", "", time() - 3600);
setcookie("iMISEmail", "", time() - 3600);
setcookie("iMISMember", "", time() - 3600);
return false

I presume that this is because output is in process but I do not know how to add these cookies to those that vBulletin will clear.