3 sibling joint tenancy with one dies.

You do not need to change the deed.  Joint tenancy includes rights of survivorship, so that the remaining two siblings are now the owners.  When the two siblings sell or otherwise transfer the property, the deed to the new owners should just note that the third sibling died and the date of death.  Until transfer, however, no action is required.  If you like, you can inform the town so that its records reflect the death and property tax bills and other notices are sent only to the remaining siblings.