how to remove existing infoobject from infosource?

I was added one infoobject Z01 into DSO ZDSO01 and Infosource 2LIS_08TRTLP

, and did mapping in the transfer rule. Now I removed Z01 from DSO ZDSO01, but I'm unable to remove Z01 from infosource.

System show me error message like:

The InfoObject ZO01 is still used in the following places: In routine xxxxxxxxxxx of the update rules for Data Target ZDSO01 InfoSource 2LIS_08TRTLP

Anyone know how to remove Z01 from DSO ZDSO01 in my case.

Thanks,

Sudree