Show/Hide trend line using DAX

Hi Tayyab 

Sorry the description is not clear. Can you please provide some sample data and more details to describe the requirement? https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523 

If the trend line value is calculated by a measure, you can consider using ISFILTERED or SELECTEDVALUE to tell whether a slicer is picking a value. When a value is picked, the measure calculates the correct trend value. Otherwise, make the measure return blank. 

Or you can try creating bookmarks for Show and Hide status separately. Then bind the bookmarks to buttons and use buttons to switch the bookmarks. 

Reference:

Power BI bookmarks 

Power BI buttons 

Best Regards,
Community Support Team _ Jing
If this post helps, please Accept it as Solution to help other members find it.