loaded new plugin but now cannot access my blog

I downloaded and tried to install a plugin that would add a “top of the page” button to my website pages. Bad news! Now I cannot access my website pages. There is now a whole upper half page of repeated errors that I have copied and pasted below:

Warning: fopen(/home/content/p/p/g/ppg5191/html/wp-content/plugins/return-to-top/file.txt) [function.fopen]: failed to open stream: No such file or directory in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 53

Warning: filesize() [function.filesize]: stat failed for /home/content/p/p/g/ppg5191/html/wp-content/plugins/return-to-top/file.txt in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 54

Warning: fread(): supplied argument is not a valid stream resource in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 54

Warning: fclose(): supplied argument is not a valid stream resource in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 55

Warning: fopen(/home/content/p/p/g/ppg5191/html/wp-content/plugins/return-to-top/file.txt) [function.fopen]: failed to open stream: No such file or directory in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 61

Warning: fwrite(): supplied argument is not a valid stream resource in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 62

Warning: fclose(): supplied argument is not a valid stream resource in /home/content/p/p/g/ppg5191/html/murderproductions/wordpress/wp-content/plugins/return-to-top/return-to-top.php on line 63

How do I undo this mess so my website returns to normal. I would really love to reverse the last Plug-in I added to my website since it is obviously causing all kinds of problems! I’m a somewhat new WP user, and my previous plugins caused no problems like this.

Please help!!!