Can no. 6 stranded wire that does not fit into the connection on the block can some of the strands be cut soit can fir or is this a safety issue

Cutting strands off a wire to make it fit is not allowed. Either the lug needs to be rated for the wire size, or a short piece of wire that fits can be inserted and spliced onto the larger wire. For large cable there are wire reducers available for this situation, but not available for smaller sizes such as #6.