STSADM Command to Add Template
stsadm -o addtemplate -filename SiteTemplate.stp -title "Template Title" -description "Template Description"
STSADM Command to Remove Template
stsadm -o deletetemplate -title "Template Title"
STSADM.exe can be found at :\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN\.
