I hesitate to do this on a Monday morning but, here goes.
First of all make sure that you have verified that the data on the tape is good and can be restored
If you're happy that it is, cd to the directory above the level of the directory you wish to delete is located and issue an:
rm -r <directory_name>
This will remove the directory and every file and recursive directory within it - these instructions are on the basis that this is what you want to do.
If you know the directory is empty, use rmdir <dir_name> from the level above it.
It's not too clear from your question whether you wish to restore the contents of your tape to another directory. Can you clarify the format the tape's written in (eg tar, cpio etc) and the content in terms of whether the files on it are in absolute (ie with a full pathname) or relative (ie maybe just the filename itself).