Warning: Cannot modify header information

Experiencing cache error from slimstat and I’m unable to access my site.

Error:
var_
Warning: Cannot modify header information – headers already sent by (output started at /home/user/url.com/wp-content/plugins/wp-slimstat/wp-slimstat.php:1) in /home/user/url.com/wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 62

Warning: Cannot modify header information – headers already sent by (output started at /home/user/url.com/wp-content/plugins/wp-slimstat/wp-slimstat.php:1) in /home/user/url.com/wp-includes/pluggable.php on line 1171

Please advise, thanks.

https://wordpress.org/plugins/wp-slimstat/