For a simple solution that uses just regex, you can search the following pattern and replace all occurrences of it with an empty string:
\s*<[^>]+>\s*
For instance:
p = re.compile( '\s*<[^>]+>\s*')
p.sub( '', '<span class=H>宜家</span><span class=H>同款</span> 世纪宝贝儿童餐椅婴儿餐椅宝宝餐椅婴儿吃饭椅')
Disclaimer: This will, by no means, handle every possible variation of legal HTML, but, as long as all of the input data, is as simple as the data in your example, it will work. You could make changes to the pattern, as necessary, to handle slightly more complex inputs. However, if your intent is to handle any well-formed HTML document as input, then you should consider an actual HTML parser rather than using regex.