Please if anybody can illustrate how to refresh the sd card . Thanks alot.

Does this help?

Refresh?  Just put it in a PC card reader, highlight all files, cut and move to where you want.  Card is clean after that.

Hi Kevin. Refresh/format the SD card with the DJI GO 4 app under camera settings. Scroll down to the bottom and click "Format SD Card". This will delete everything and the SD card.

Please do so above after you have saved your data to another medium.  

Jaovst Posted at 2017-12-7 09:53
Hi Kevin. Refresh/format the SD card with the DJI GO 4 app under camera settings. Scroll down to the bottom and click "Format SD Card". This will delete everything and the SD card.

Strictly speaking your reply is incorrect.
When you format an SD card, nothing is deleted, but the FAT is initialized.
All the data is still on the card.
This is important, because if you accidentally format an SD card, recovery software exists to recover all of the data on that memory card, if you do the recovery immediately after formatting the SD card.

Hi, thanks for the replies above, good job.
Kevin, please refer to the answers above, you can both format it in DJI GO app and connect the drone to the PC and format it.

How can I delete the files on SD card I want with the DJI Go 4 app? Using an iPad.

swoondrones Posted at 12-28 14:30
How can I delete the files on SD card I want with the DJI Go 4 app? Using an iPad.

Put the card into your PC and slide all files into the trash, then delete, or whatever else you want.

swoondrones Posted at 12-28 14:30
How can I delete the files on SD card I want with the DJI Go 4 app? Using an iPad.

Just curious, did you read any of the comments in this thread?? The video referenced in comment #2 plus the instructions in post #4 pretty much cover your question.

swoondrones Posted at 12-28 14:30
How can I delete the files on SD card I want with the DJI Go 4 app? Using an iPad.

If you are talking about microSD card in Mavic, GO-4 has option to Format microSD card.