re = /(THE END|FINIS).*/
str = 'txt <- "... thou hast tam\'d a curst shrow. LUCENTIO. \'Tis a wonder,
by your leave, she will be tam\'d so. Exeunt THE END <<THIS ELECTRONIC VERSION OF THE COMPLETE WORKS OF WILLIAM ..."
txt <- "... thou hast tam\'d a curst shrow. LUCENTIO. \'Tis a wonder,
by your leave, she will be tam\'d so. Exeunt FINIS <<THIS ELECTRONIC VERSION OF THE COMPLETE WORKS OF WILLIAM ..."'
subst = ''
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html