re = /\b[a-zA-Z]{1,2}\d{3,5}[a-zA-Z]?\b/m
str = 'M394
,MP4245)
TD493!
X4958A
V49534@
U394U
A5909.
TED492
R32
R4!3
U394UU
A5909AA
5349A'
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