1. If you just don't want to use 2K for the time being, you only need to use "sys c:" to transfer the system back to drive C where 98 is located, and then the multi-boot menu will no longer appear.
2. If you want to remove 2K completely, then under DOS you also need to use related software (such as PQmagic) to delete the NTFS partition where 2K is located; or you can run 2K's installer in 98, and after it finishes copying the temporary files and restarts, choose "New Installation". When it prompts you to select a partition, delete the original partition where 2K is located, then exit.