Based on this question Why do we need Intel SSD Toolbox for TRIM? it seems that there is no need to use vendor's application to trim.
But although I'm sure Windows 10 trim is not disabled but in WD Dashboard there is a checkbox "enable trim" which is not checked so now I'm not sure what is the real status of trim.
My way to check trim is from online:
fsutil behavior query DisableDeleteNotify
the result is "0(disabled)", which means trim is enabled. I'm not sure whether this is enough and why there isn't an UI to show information as important as this.
Another question is will windows do trim when I delete a whole partition?