There should be no space between the URL-path pattern and its end-anchor, or preceding the "?" on the substitution URL.
# Externally redirect to remove query string from /folder/New.jsp?<optional_parms&>par=new1<&optional_parms>
RewriteCond %{QUERY_STRING} ^([^&]*&)*par=new1(&.*)?$
RewriteRule ^folder/New\.jsp$ https://www.website.com/folder/New.jsp? [R=301,L]
Also, escape all literal periods in regex patterns, and use "soft anchors" to unambiguously match your query string, even if preceded/surrounded/followed by any other name/value pairs.
This assumes that this code is going into www.website.com/.htaccess and that you already have other working rewriterules in that file. If not, you need to say so. Also, "Not successful" is not a very useful error report. To resolve this problem quickly, please provide detail on your test method, expected results, actual results, and differences between the expected and actual results.
Jim