import re
text = "This is a string <code>1234</code> another string <code>123</code> another string <code>123456789</code> another string."
text = re.sub("<code>[^>]{6,}</code>", '', text)
print(text)
aW1wb3J0IHJlCnRleHQgPSAiVGhpcyBpcyBhIHN0cmluZyA8Y29kZT4xMjM0PC9jb2RlPiBhbm90aGVyIHN0cmluZyA8Y29kZT4xMjM8L2NvZGU+IGFub3RoZXIgc3RyaW5nIDxjb2RlPjEyMzQ1Njc4OTwvY29kZT4gYW5vdGhlciBzdHJpbmcuIgp0ZXh0ID0gcmUuc3ViKCI8Y29kZT5bXj5dezYsfTwvY29kZT4iLCAnJywgdGV4dCkKcHJpbnQodGV4dCkK