Force delete instance in create script

Change-Id: I692f9b214d36a151f733c0805ed2b6768a817141

create.sh

diff --git a/create.sh b/create.sh
index 63957b7..e24e195 100755
--- a/create.sh
+++ b/create.sh
@@ -20,6 +20,8 @@
 name=pluginbuilder
 
 gcutil --project $project deleteinstance \
+    --force \
+    --delete_boot_pd \
     --zone=$zone \
     $name