re = /<((?!a|\/a)[^>]*)>\s*/m
str = '<html>
<head>
<meta http-equiv=\\"Content-Type\\" content=\\"text/html; charset=utf-8\\">
<meta content=\\"text/html; charset=us-ascii\\">
<meta name=\\"ProgId\\" content=\\"Word.Document\\">
<meta name=\\"Generator\\" content=\\"Microsoft Word 15\\">
<meta name=\\"Originator\\" content=\\"Microsoft Word 15\\">
<style>
<!--
@font-face
\\t{font-family:\\"Cambria Math\\"}
@font-face
\\t{font-family:Calibri}
p.MsoNormal, li.MsoNormal, div.MsoNormal
\\t{margin:0cm;
\\tmargin-bottom:.0001pt;
\\tfont-size:11.0pt;
\\tfont-family:\\"Calibri\\",sans-serif}
a:link, span.MsoHyperlink
\\t{color:#0563C1;
\\ttext-decoration:underline}
a:visited, span.MsoHyperlinkFollowed
\\t{color:#954F72;
\\ttext-decoration:underline}
p.msonormal0, li.msonormal0, div.msonormal0
\\t{margin-right:0cm;
\\tmargin-left:0cm;
\\tfont-size:11.0pt;
\\tfont-family:\\"Calibri\\",sans-serif}
span.EmailStyle18
\\t{font-family:\\"Calibri\\",sans-serif}
.MsoChpDefault
\\t{font-size:10.0pt;
\\tfont-family:\\"Calibri\\",sans-serif}
@page WordSection1
\\t{margin:72.0pt 72.0pt 72.0pt 72.0pt}
div.WordSection1
\\t{}
-->
</style>
</head>
<body lang=\\"EN-GB\\" link=\\"#0563C1\\" vlink=\\"#954F72\\" style=\\"\\">
<div class=\\"WordSection1\\">
<p class=\\"MsoNormal\\">I NEED TO HAVE THIS STRING</p>
<p class=\\"MsoNormal\\"> </p>
<p class=\\"MsoNormal\\"><span style=\\"\\">AND I NEED THE FOLLOWING ANCHOR
<a href=\\"google.com\\">
THIS ONE</a>.</span></p>
<p class=\\"MsoNormal\\"> </p>
</div>
</body>
</html>
'
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