Upgrade Problem – Please Help!

I lagged on upgrading my site and now when I go to login so I can get things up to date I get the following error:

“This plugin requires WordPress version 3.3.1 or newer. Please upgrade your WordPress installation or download an older version of the plugin.

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-login.php on line 353

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-login.php on line 365

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-includes/pluggable.php on line 737

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-includes/pluggable.php on line 738

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-includes/pluggable.php on line 739

Warning: Cannot modify header information – headers already sent by (output started at /home/invault/www/www/main/wp-content/plugins/ultimate-tinymce/main.php:95) in /home/invault/www/www/main/wp-includes/pluggable.php on line 934″

How can I upgrade to the current version of WordPress if I can’t access the Dashboard? I looked into doing a manual upgrade, however the instructions stated that it’s imperative to disable all plugin-ins first, which I cannot do if I cannot get into my dashboard.

Please help.