re = /(?:\d+[a-z]|[a-z]+\d)[a-z\d]*/m
str = 'asdasdas7
7sdfdf
a1
1a
0001a
0000a0000
a-1
1-a
a
1
eee
21123124
aaaa-111
1 a 6858 ghg 8768-zzt zz zt t-3
1212231234_sdfs1111dfsdf_ewrwerfwe_sef3325345'
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