Unable to move malware to iMac's bin

+1 on WheelieNick's post. Get the free version of Malwarebytes. However, then again are you positive you have installed some malware? I would recommend doing the following first.

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate towww.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

If you're sure that you have malware on your Mac you might want to install the free version of malwarebytes anti malware to see if you can get rid of it using that

If you see it again, post the free EtreCheck report using the link provided by rkaufmann87 titled "How to Use the Add Text Feature When Post..." and if you have any suspicious files launching on startup, they will be identified there.

What file are you trying to delete and where is it currently located?

What malware are you trying to delete?