You could also use this,
sed 's/^\([^<]*\)<.*>\(.*\)$/\1\2/g' file
Explanation:
^\([^<]*\)< - Fetches any charcter not of < zero or more times from the starting position upto < and finally stores the fetched characters into a group.
.*> - Matches any character zero or more times until it finds >.
\(.*\)$ - Once the sed finds > character, it starts to store all the characters which are next to > upto the last into another group(stores characters inbetween > and $).
Finally sed prints only the stored groups(\1,\2) through back-reference.
Example:
$ cat file.txt
FOO<td align="right" style='mso-number-format:"\[$-409\]m\/d\/yy\\ h\:mm\\ AM\/PM\;\@";' x:str>BAR
$ sed 's/^\([^<]*\)<.*>\(.*\)$/\1\2/g' file.txt
FOOBAR
