If you use the matplotlib object-oriented approach, this is a simple task using ax.set_xticklabels() and ax.set_yticklabels(). Here we can just set them to an empty list to remove any labels:
import matplotlib.pyplot as plt
# Create Figure and Axes instances
fig,ax = plt.subplots(1)
# Make your plot, set your axes labels
ax.plot(sim_1['t'],sim_1['V'],'k')
ax.set_ylabel('V')
ax.set_xlabel('t')
# Turn off tick labels
ax.set_yticklabels([])
ax.set_xticklabels([])
plt.show()
If you also want to remove the tick marks as well as the labels, you can use ax.set_xticks() and ax.set_yticks() and set those to an empty list as well:
ax.set_xticks([])
ax.set_yticks([])