Hi Deli,
Thank you for your interest in Syncfusion products.
I am not able to reproduce the issue that you mentioned here. I have created a simple sample and delete some section of rows and columns from the sheet and open the resaved template file. Here it works without any exception. Please refer the sample in the below link:
http://www.syncfusion.com/development/uploads/XlsIO_Win_DeleteRows_971af7e9.zipPlease take a look into the above sample and try reproducing it in the above sample and send us the modified sample so that we could sort out the cause of the issue and provide you a solution?
Regards,
G.Yavana