I asked you about Version of SQL Server and you did not responded, the reason I asked it because if you are running RTM version of SQL Server or your SQL Server is not patched to latest Service Pack and cumulative update there is no point in opening case with Microsoft. If you do so the Microsoft Engineer or the support personal would first ask you to apply latest SP.
Other scenario is if you have not updated your SQL Server to latest SP, for instance for SQL Server 2012 you have SP3 released and you are still on SP1 and you log a case with Microsoft for this issue you would be charged and its quite possible the support guy would say this is known issues and is fixed in Sp3. So you would end up wasting money. So I strongly suggest you to check whether the SQL Server is on latest SP.
I also wanted to check whether you are actually running supported version of SQL Server or not. The way it is creating dump I have hunch that you are running SQL Server which is not patched to latest SP
If the SQL Server is patched to latest SP and still it is crashing producing stack dumps I would suggest you to open case with Microsoft they are the best in terms of analyzing the stack dump file and would surely tell you the reason. Unless you are really good with analyzing dumps I would not suggest you to waste time in doing so.
I can share with you few blogs which would give you some hint on how to analyze the dumps
Not all crash dumps are because of bug in SQL Server many occur due to poorly configured SQL Server or some rouge queries running. But since you have not shared detailed errorlog it is difficult to say at this point. Make sure your SQL Server is configured correctly. Again if such is the case MS support will point this out.
If SQL Server is not updated with latest SP first update it, look for the cumulative updates released after the SP(you can get that from first link I have shared) and make sure bug you are facing is not fixed in CU releases ONLY then open case with Microsoft.
can I delete them and if it is good thing to do ?
If you are planning to open case with Microsoft I suggest you move them to some other location just in case. If you have those dumps you can give more information to support personal who would be looking at your case. Also note that its quite likely that the dump produced would not capture all information related to the issue and support personal would ask you to enable trace flag and wait for the next dump to occur which will capture all the related information.
If you really like to delete it, delete the old ones and leave the new ones.