Hi Priom,
Thank you for contacting Syncfusion support
To disable the borders in the SfAccordionItem, you have to set its BorderThickness to 0 in the ItemsContainerStyle of the SfAccordion. We have prepared a sample that demonstrates the same. You can download the sample from the following
Sample link:
SfAccordionBorderSample Please let us know if you need any other assistance
Regards,
M.Sugapriya