Hi @Ayan ,
If you can share your error log, you will get more information about the error, it is located at:\Program Files\Microsoft SQL Server\MSSQLV.SQLEXPRESS\MSSQL\Log\ERRORLOG
For this error, you can check the file name of the setup exe first, if it is ssms.exe, please rename it to anything else
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/2908b402-4b8b-4101-8883-46c759067858/ssms-install-fails-with-error-ssms-is-currently-running-please-close-any-open-instances-of-ssms?forum=sqltools
And remember close any open instances of SSMS and install again
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